<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <title>Digestive System Sequence</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      background: #ffffff;
      color: #1e2945;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
    }
    .top-bar {
      width: 100%;
      max-width: 620px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      margin-bottom: 10px;
      gap: 8px;
    }
    .status-badge {
      display: flex;
      align-items: center;
      gap: 6px;
      font-size: 14px;
      font-weight: 700;
      color: #1e2945;
      background: #f1f5f9;
      padding: 6px 12px;
      border-radius: 20px;
    }
    .food-dot {
      font-size: 16px;
      line-height: 1;
    }
    .controls {
      display: flex;
      gap: 6px;
    }
    .btn {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      color: #1e2945;
      font-size: 13px;
      font-weight: 600;
      padding: 6px 12px;
      border-radius: 8px;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 4px;
      user-select: none;
      transition: background-color 0.2s, border-color 0.2s;
    }
    .btn:hover {
      background: #f8fafc;
      border-color: #94a3b8;
    }
    .btn-primary {
      background: #22b7ff;
      border-color: #0ea5e9;
      color: #ffffff;
    }
    .btn-primary:hover {
      background: #0ea5e9;
    }

    /* Cards Grid */
    .grid {
      width: 100%;
      max-width: 620px;
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 8px;
      margin-bottom: 8px;
    }

    @media (max-width: 520px) {
      .grid {
        grid-template-columns: repeat(2, 1fr);
      }
    }

    .card {
      background: #f8fafc;
      border: 2px solid transparent;
      border-radius: 10px;
      padding: 8px 6px;
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      cursor: pointer;
      position: relative;
      user-select: none;
      transition: background-color 0.25s, border-color 0.25s, box-shadow 0.25s;
      min-height: 86px;
      justify-content: center;
    }

    .card:hover {
      background: #f1f5f9;
    }

    .card.active {
      background: #ffffff;
      border-color: #22b7ff;
      box-shadow: 0 4px 12px rgba(34, 183, 255, 0.25);
    }

    .card-num {
      position: absolute;
      top: 4px;
      left: 6px;
      font-size: 11px;
      font-weight: 800;
      color: #94a3b8;
    }
    .card.active .card-num {
      color: #0284c7;
    }

    .card-icon {
      font-size: 20px;
      line-height: 1;
      margin-bottom: 4px;
      margin-top: 2px;
    }

    .card-title {
      font-size: 13px;
      font-weight: 700;
      color: #1e2945;
      line-height: 1.15;
    }

    .card-desc {
      font-size: 11px;
      color: #64748b;
      margin-top: 3px;
      line-height: 1.1;
      font-weight: 500;
    }

    .card.active .card-desc {
      color: #0369a1;
      font-weight: 600;
    }

    /* Step Dots */
    .dots-track {
      display: flex;
      gap: 6px;
      align-items: center;
      justify-content: center;
      margin-top: 4px;
    }
    .dot-btn {
      width: 12px;
      height: 12px;
      border-radius: 50%;
      background: #e2e8f0;
      border: none;
      cursor: pointer;
      padding: 0;
      transition: background-color 0.25s, transform 0.2s;
    }
    .dot-btn:hover {
      background: #cbd5e1;
    }
    .dot-btn.active {
      background: #22b7ff;
      transform: scale(1.25);
    }
  </style>
</head>
<body>

  <div class="top-bar">
    <div class="status-badge" id="statusBadge">
      <span class="food-dot" id="foodEmoji">🍎</span>
      <span id="stepLabel">1. Mouth</span>
    </div>
    <div class="controls">
      <button class="btn" id="prevBtn" onclick="stepPrev()" aria-label="Previous">◀</button>
      <button class="btn btn-primary" id="playBtn" onclick="togglePlay()" aria-label="Play/Pause">⏸ Pause</button>
      <button class="btn" id="nextBtn" onclick="stepNext()" aria-label="Next">▶</button>
    </div>
  </div>

  <div class="grid" id="cardsGrid">
    <div class="card active" onclick="goToStep(0)">
      <span class="card-num">1</span>
      <div class="card-icon">👄</div>
      <div class="card-title">Mouth</div>
      <div class="card-desc">Chews food</div>
    </div>

    <div class="card" onclick="goToStep(1)">
      <span class="card-num">2</span>
      <div class="card-icon">⬇️</div>
      <div class="card-title">Esophagus</div>
      <div class="card-desc">Carries food</div>
    </div>

    <div class="card" onclick="goToStep(2)">
      <span class="card-num">3</span>
      <div class="card-icon">🥣</div>
      <div class="card-title">Stomach</div>
      <div class="card-desc">Churns with acid</div>
    </div>

    <div class="card" onclick="goToStep(3)">
      <span class="card-num">4</span>
      <div class="card-icon">✨</div>
      <div class="card-title">Small Intestine</div>
      <div class="card-desc">Absorbs nutrients</div>
    </div>

    <div class="card" onclick="goToStep(4)">
      <span class="card-num">5</span>
      <div class="card-icon">💧</div>
      <div class="card-title">Large Intestine</div>
      <div class="card-desc">Absorbs water</div>
    </div>

    <div class="card" onclick="goToStep(5)">
      <span class="card-num">6</span>
      <div class="card-icon">📦</div>
      <div class="card-title">Rectum</div>
      <div class="card-desc">Stores solid waste</div>
    </div>

    <div class="card" onclick="goToStep(6)">
      <span class="card-num">7</span>
      <div class="card-icon">🚪</div>
      <div class="card-title">Anus</div>
      <div class="card-desc">Releases waste</div>
    </div>
  </div>

  <div class="dots-track" id="dotsTrack">
    <button class="dot-btn active" onclick="goToStep(0)" aria-label="Go to step 1"></button>
    <button class="dot-btn" onclick="goToStep(1)" aria-label="Go to step 2"></button>
    <button class="dot-btn" onclick="goToStep(2)" aria-label="Go to step 3"></button>
    <button class="dot-btn" onclick="goToStep(3)" aria-label="Go to step 4"></button>
    <button class="dot-btn" onclick="goToStep(4)" aria-label="Go to step 5"></button>
    <button class="dot-btn" onclick="goToStep(5)" aria-label="Go to step 6"></button>
    <button class="dot-btn" onclick="goToStep(6)" aria-label="Go to step 7"></button>
  </div>

  <script>
    const stepData = [
      { num: 1, name: 'Mouth', emoji: '🍎' },
      { num: 2, name: 'Esophagus', emoji: '🍏' },
      { num: 3, name: 'Stomach', emoji: '🥣' },
      { num: 4, name: 'Small Intestine', emoji: '✨' },
      { num: 5, name: 'Large Intestine', emoji: '💧' },
      { num: 6, name: 'Rectum', emoji: '📦' },
      { num: 7, name: 'Anus', emoji: '🚪' }
    ];

    let currentStep = 0;
    let isPlaying = true;
    let timer = null;

    const cards = document.querySelectorAll('.card');
    const dots = document.querySelectorAll('.dot-btn');
    const stepLabel = document.getElementById('stepLabel');
    const foodEmoji = document.getElementById('foodEmoji');
    const playBtn = document.getElementById('playBtn');

    function updateUI() {
      cards.forEach((c, idx) => {
        if (idx === currentStep) {
          c.classList.add('active');
        } else {
          c.classList.remove('active');
        }
      });

      dots.forEach((d, idx) => {
        if (idx === currentStep) {
          d.classList.add('active');
        } else {
          d.classList.remove('active');
        }
      });

      const curr = stepData[currentStep];
      stepLabel.textContent = `${curr.num}. ${curr.name}`;
      foodEmoji.textContent = curr.emoji;
    }

    function goToStep(idx) {
      currentStep = (idx + stepData.length) % stepData.length;
      updateUI();
    }

    function stepNext() {
      goToStep(currentStep + 1);
    }

    function stepPrev() {
      goToStep(currentStep - 1);
    }

    function startAutoPlay() {
      if (timer) clearInterval(timer);
      timer = setInterval(() => {
        stepNext();
      }, 3000);
    }

    function togglePlay() {
      isPlaying = !isPlaying;
      if (isPlaying) {
        playBtn.textContent = '⏸ Pause';
        startAutoPlay();
      } else {
        playBtn.textContent = '▶ Play';
        clearInterval(timer);
        timer = null;
      }
    }

    // Start on step 1 with auto cycling
    startAutoPlay();
  </script>
</body>
</html>

The Human Digestive System: Organs and Overview

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <title>The Digestive Tract</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      -webkit-tap-highlight-color: transparent;
    }

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #f8fafc;
      color: #1e2945;
      width: 100%;
      min-height: 100%;
      display: flex;
      flex-direction: column;
      justify-content: center;
      padding: 10px;
    }

    .main-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 12px;
      align-items: center;
      max-width: 600px;
      margin: 0 auto;
      width: 100%;
    }

    /* Left: Flowchart */
    .flowchart {
      display: flex;
      flex-direction: column;
      gap: 5px;
    }

    .step-btn {
      display: flex;
      align-items: center;
      gap: 8px;
      padding: 6px 10px;
      background: #ffffff;
      border: 1.5px solid #e2e8f0;
      border-radius: 8px;
      cursor: pointer;
      font-size: 13px;
      font-weight: 600;
      color: #475569;
      text-align: left;
      transition: background-color 0.2s ease, border-color 0.2s ease, color 0.2s ease, box-shadow 0.2s ease;
      user-select: none;
      width: 100%;
    }

    .step-num {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      width: 20px;
      height: 20px;
      border-radius: 50%;
      background: #f1f5f9;
      color: #64748b;
      font-size: 11px;
      font-weight: 700;
      flex-shrink: 0;
    }

    .step-btn.active {
      background: #f0f9ff;
      border-color: #0284c7;
      color: #0369a1;
      box-shadow: 0 2px 6px rgba(2, 132, 199, 0.15);
    }

    .step-btn.active .step-num {
      background: #0284c7;
      color: #ffffff;
    }

    /* Right: Body Graphic */
    .view-panel {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 8px;
      position: relative;
    }

    .body-wrapper {
      position: relative;
      width: 100%;
      max-width: 220px;
      aspect-ratio: 1 / 1.5;
      background: #ffffff;
      border: 1.5px solid #e2e8f0;
      border-radius: 12px;
      padding: 6px;
      display: flex;
      align-items: center;
      justify-content: center;
      box-shadow: 0 1px 3px rgba(0,0,0,0.04);
    }

    svg {
      width: 100%;
      height: 100%;
      overflow: visible;
    }

    /* Organ Styles */
    .organ {
      fill-opacity: 0.25;
      stroke-width: 2.5;
      transition: fill-opacity 0.3s ease, stroke-width 0.3s ease, filter 0.3s ease;
      cursor: pointer;
    }

    .organ.active {
      fill-opacity: 0.95;
      stroke-width: 3.5;
      filter: drop-shadow(0 0 5px rgba(2, 132, 199, 0.5));
    }

    /* Organ specific colours */
    .organ-mouth { fill: #f43f5e; stroke: #e11d48; }
    .organ-esophagus { fill: #f97316; stroke: #ea580c; stroke-width: 3.5; }
    .organ-stomach { fill: #eab308; stroke: #ca8a04; }
    .organ-small-int { fill: #10b981; stroke: #059669; }
    .organ-large-int { fill: #8b5cf6; stroke: #7c3aed; }
    .organ-rectum { fill: #06b6d4; stroke: #0891b2; stroke-width: 3.5; }
    .organ-anus { fill: #ec4899; stroke: #db2777; }

    /* Food bolus */
    .food-dot {
      fill: #ef4444;
      stroke: #ffffff;
      stroke-width: 2;
      filter: drop-shadow(0 0 4px #ef4444);
      transition: cx 0.5s ease, cy 0.5s ease;
    }

    /* Function Badge */
    .badge {
      min-height: 38px;
      width: 100%;
      max-width: 220px;
      background: #0f172a;
      color: #f8fafc;
      font-size: 12px;
      font-weight: 500;
      border-radius: 8px;
      display: flex;
      align-items: center;
      justify-content: center;
      text-align: center;
      padding: 6px 10px;
      box-shadow: 0 2px 4px rgba(15, 23, 42, 0.15);
      transition: opacity 0.2s ease;
    }

    /* Controls */
    .controls {
      display: flex;
      justify-content: center;
      gap: 8px;
      margin-top: 6px;
    }

    .ctrl-btn {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 6px;
      padding: 4px 10px;
      font-size: 12px;
      font-weight: 600;
      color: #334155;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 4px;
    }

    .ctrl-btn:active {
      background: #f1f5f9;
    }

    @media (max-width: 440px) {
      .main-grid {
        grid-template-columns: 1.1fr 0.9fr;
        gap: 8px;
      }
      .step-btn {
        padding: 4px 6px;
        font-size: 11.5px;
      }
      .step-num {
        width: 16px;
        height: 16px;
        font-size: 10px;
      }
      .badge {
        font-size: 11px;
        min-height: 34px;
        padding: 4px 6px;
      }
    }
  </style>
</head>
<body>

  <div class="main-grid">
    
    <div class="flowchart" id="flowchart">
      <button class="step-btn active" data-index="0">
        <span class="step-num">1</span> Mouth
      </button>
      <button class="step-btn" data-index="1">
        <span class="step-num">2</span> Oesophagus
      </button>
      <button class="step-btn" data-index="2">
        <span class="step-num">3</span> Stomach
      </button>
      <button class="step-btn" data-index="3">
        <span class="step-num">4</span> Small Intestine
      </button>
      <button class="step-btn" data-index="4">
        <span class="step-num">5</span> Large Intestine
      </button>
      <button class="step-btn" data-index="5">
        <span class="step-num">6</span> Rectum
      </button>
      <button class="step-btn" data-index="6">
        <span class="step-num">7</span> Anus
      </button>

      <div class="controls">
        <button class="ctrl-btn" id="playBtn">⏸ Pause</button>
      </div>
    </div>

    
    <div class="view-panel">
      <div class="body-wrapper">
        <svg viewBox="0 0 160 240">
          
          <path d="M 80 18 
                   C 88 18, 95 24, 95 34 
                   C 95 42, 89 48, 86 52 
                   C 96 54, 114 62, 120 78 
                   L 115 130 
                   C 114 140, 112 180, 110 215 
                   C 98 220, 90 220, 80 220 
                   C 70 220, 62 220, 50 215 
                   C 48 180, 46 140, 45 130 
                   L 40 78 
                   C 46 62, 64 54, 74 52 
                   C 71 48, 65 42, 65 34 
                   C 65 24, 72 18, 80 18 Z" 
                fill="#f1f5f9" stroke="#cbd5e1" stroke-width="2" stroke-linejoin="round" />

          
          <path d="M 80 36 
                   L 80 75 
                   C 80 85, 92 85, 92 98 
                   C 92 108, 70 108, 70 118 
                   C 70 135, 90 135, 90 148 
                   C 90 162, 80 162, 80 178 
                   L 80 196" 
                fill="none" stroke="#e2e8f0" stroke-dasharray="3,3" stroke-width="1.5" />

          
          <ellipse id="organ-0" class="organ organ-mouth active" cx="80" cy="36" rx="7" ry="5" />

          
          <line id="organ-1" class="organ organ-esophagus" x1="80" y1="42" x2="80" y2="76" />

          
          <path id="organ-2" class="organ organ-stomach" 
                d="M 80 76 
                   C 68 76, 62 88, 65 100 
                   C 68 112, 88 112, 92 100 
                   C 94 92, 88 84, 80 76 Z" />

          
          <path id="organ-4" class="organ organ-large-int" 
                d="M 64 160 
                   L 64 124 
                   C 64 118, 96 118, 96 124 
                   L 96 160" 
                fill="none" stroke-linecap="round" stroke-linejoin="round" stroke-width="6" />

          
          <path id="organ-3" class="organ organ-small-int" 
                d="M 76 126 
                   Q 84 130, 76 135 
                   Q 68 140, 80 145 
                   Q 88 148, 78 152 
                   Q 72 155, 80 158" 
                fill="none" stroke-linecap="round" stroke-width="5" />

          
          <line id="organ-5" class="organ organ-rectum" x1="80" y1="166" x2="80" y2="186" />

          
          <circle id="organ-6" class="organ organ-anus" cx="80" cy="192" r="4.5" />

          
          <circle id="foodDot" class="food-dot" cx="80" cy="36" r="4" />
        </svg>
      </div>

      
      <div id="functionBadge" class="badge">Chews and breaks down food</div>
    </div>
  </div>

  <script>
    const steps = [
      { name: "Mouth", action: "Chews and moistens food with saliva", x: 80, y: 36 },
      { name: "Oesophagus", action: "Pushes food down into the stomach", x: 80, y: 59 },
      { name: "Stomach", action: "Churns food with digestive acid", x: 77, y: 94 },
      { name: "Small Intestine", action: "Absorbs nutrients into the blood", x: 78, y: 142 },
      { name: "Large Intestine", action: "Absorbs water and forms waste", x: 64, y: 130 },
      { name: "Rectum", action: "Stores solid waste before exit", x: 80, y: 176 },
      { name: "Anus", action: "Releases waste from the body", x: 80, y: 192 }
    ];

    let currentIndex = 0;
    let isPlaying = true;
    let timer = null;

    const stepButtons = document.querySelectorAll('.step-btn');
    const badge = document.getElementById('functionBadge');
    const dot = document.getElementById('foodDot');
    const playBtn = document.getElementById('playBtn');

    function setStep(index) {
      currentIndex = index;

      // Update button styles
      stepButtons.forEach((btn, idx) => {
        btn.classList.toggle('active', idx === index);
      });

      // Update organ glows
      for (let i = 0; i < 7; i++) {
        const organ = document.getElementById(`organ-${i}`);
        if (organ) {
          organ.classList.toggle('active', i === index);
        }
      }

      // Move food dot
      dot.setAttribute('cx', steps[index].x);
      dot.setAttribute('cy', steps[index].y);

      // Update badge text
      badge.style.opacity = '0';
      setTimeout(() => {
        badge.textContent = steps[index].action;
        badge.style.opacity = '1';
      }, 150);
    }

    function nextStep() {
      const next = (currentIndex + 1) % steps.length;
      setStep(next);
    }

    function startAutoPlay() {
      stopAutoPlay();
      timer = setInterval(nextStep, 3200);
      isPlaying = true;
      playBtn.textContent = '⏸ Pause';
    }

    function stopAutoPlay() {
      if (timer) {
        clearInterval(timer);
        timer = null;
      }
      isPlaying = false;
      playBtn.textContent = '▶ Play';
    }

    // Step button click handlers
    stepButtons.forEach((btn) => {
      btn.addEventListener('click', () => {
        const idx = parseInt(btn.getAttribute('data-index'), 10);
        setStep(idx);
        if (isPlaying) {
          startAutoPlay(); // reset timer
        }
      });
    });

    // Organ SVG click handlers
    for (let i = 0; i < 7; i++) {
      const organ = document.getElementById(`organ-${i}`);
      if (organ) {
        organ.addEventListener('click', () => {
          setStep(i);
          if (isPlaying) {
            startAutoPlay();
          }
        });
      }
    }

    // Play/Pause toggle
    playBtn.addEventListener('click', () => {
      if (isPlaying) {
        stopAutoPlay();
      } else {
        nextStep();
        startAutoPlay();
      }
    });

    // Start on load
    startAutoPlay();
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <title>Skeletal Protection</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      background: #f8fafc;
      color: #1e2945;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100%;
    }
    .grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 12px;
      width: 100%;
      max-width: 660px;
    }
    @media (max-width: 520px) {
      .grid {
        grid-template-columns: 1fr;
        gap: 10px;
      }
    }
    .protect-card {
      background: #ffffff;
      border: 2px solid #e2e8f0;
      border-radius: 14px;
      padding: 12px 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      cursor: pointer;
      position: relative;
      transition: border-color 0.25s ease, box-shadow 0.25s ease, transform 0.2s ease;
      user-select: none;
    }
    .protect-card.active {
      border-color: #22b7ff;
      box-shadow: 0 4px 16px rgba(34, 183, 255, 0.2);
    }
    .badge {
      position: absolute;
      top: 8px;
      right: 8px;
      font-size: 13px;
      background: #e0f2fe;
      color: #0284c7;
      padding: 2px 6px;
      border-radius: 12px;
      font-weight: 700;
      display: flex;
      align-items: center;
      gap: 3px;
      box-shadow: 0 0 8px rgba(34, 183, 255, 0.35);
    }
    .stage {
      width: 100%;
      height: 110px;
      position: relative;
      display: flex;
      align-items: center;
      justify-content: center;
      margin: 8px 0;
    }
    .organ-wrap {
      position: relative;
      width: 90px;
      height: 90px;
      display: flex;
      align-items: center;
      justify-content: center;
    }
    .bone-shield {
      position: absolute;
      inset: 0;
      pointer-events: none;
      transition: opacity 0.3s ease, filter 0.3s ease;
    }
    .protect-card.active .bone-shield {
      filter: drop-shadow(0 0 6px #22b7ff);
    }
    .label {
      font-size: 14px;
      font-weight: 700;
      color: #0f172a;
      line-height: 1.25;
      margin-top: 4px;
    }
    .sublabel {
      font-size: 12px;
      color: #0284c7;
      font-weight: 600;
      margin-top: 4px;
    }
    @keyframes pulseHeart {
      0%, 100% { transform: scale(1); }
      50% { transform: scale(1.08); }
    }
    .beating {
      animation: pulseHeart 1.2s ease-in-out infinite;
      display: inline-block;
    }
    .action-prompt {
      margin-top: 8px;
      font-size: 12px;
      color: #64748b;
      font-weight: 500;
    }
  </style>
</head>
<body>

  <div class="grid">
    
    <div class="protect-card active" onclick="selectCard(0)" id="card-0">
      <div class="badge">🛡️ Shield</div>
      <div class="stage">
        <div class="organ-wrap">
          
          <div style="font-size: 40px; transform: translateY(2px);">🧠</div>
          
          <svg class="bone-shield" viewBox="0 0 100 100">
            <path d="M 22 56 C 18 25, 82 25, 78 56 C 76 68, 68 76, 50 76 C 32 76, 24 68, 22 56 Z" 
                  fill="none" stroke="#22b7ff" stroke-width="6" stroke-linecap="round"/>
            <path d="M 38 32 C 45 28, 55 28, 62 32" fill="none" stroke="#cbd5e1" stroke-width="2"/>
          </svg>
        </div>
      </div>
      <div class="label">Skull protects<br>Brain</div>
      <div class="sublabel">Hard Cranium</div>
    </div>

    
    <div class="protect-card" onclick="selectCard(1)" id="card-1">
      <div class="badge">🛡️ Shield</div>
      <div class="stage">
        <div class="organ-wrap">
          
          <div style="font-size: 26px; display: flex; gap: 2px; align-items: center; justify-content: center;">
            <span>🫁</span>
            <span class="beating">❤️</span>
          </div>
          
          <svg class="bone-shield" viewBox="0 0 100 100">
            
            <line x1="50" y1="20" x2="50" y2="78" stroke="#cbd5e1" stroke-width="4" stroke-linecap="round"/>
            
            <path d="M 50 30 C 26 26, 20 42, 50 48" fill="none" stroke="#22b7ff" stroke-width="4" stroke-linecap="round"/>
            <path d="M 50 30 C 74 26, 80 42, 50 48" fill="none" stroke="#22b7ff" stroke-width="4" stroke-linecap="round"/>
            <path d="M 50 46 C 22 42, 18 60, 50 64" fill="none" stroke="#22b7ff" stroke-width="4" stroke-linecap="round"/>
            <path d="M 50 46 C 78 42, 82 60, 50 64" fill="none" stroke="#22b7ff" stroke-width="4" stroke-linecap="round"/>
            <path d="M 50 62 C 26 58, 22 74, 50 76" fill="none" stroke="#22b7ff" stroke-width="3.5" stroke-linecap="round"/>
            <path d="M 50 62 C 74 58, 78 74, 50 76" fill="none" stroke="#22b7ff" stroke-width="3.5" stroke-linecap="round"/>
          </svg>
        </div>
      </div>
      <div class="label">Rib Cage protects<br>Heart &amp; Lungs</div>
      <div class="sublabel">Bone Cage</div>
    </div>

    
    <div class="protect-card" onclick="selectCard(2)" id="card-2">
      <div class="badge">🛡️ Shield</div>
      <div class="stage">
        <div class="organ-wrap">
          
          <div style="position: absolute; width: 8px; height: 72px; background: #fbbf24; border-radius: 4px; box-shadow: 0 0 6px #f59e0b;"></div>
          
          <svg class="bone-shield" viewBox="0 0 100 100">
            
            <rect x="34" y="18" width="32" height="10" rx="4" fill="none" stroke="#22b7ff" stroke-width="3.5"/>
            <rect x="34" y="32" width="32" height="10" rx="4" fill="none" stroke="#22b7ff" stroke-width="3.5"/>
            <rect x="34" y="46" width="32" height="10" rx="4" fill="none" stroke="#22b7ff" stroke-width="3.5"/>
            <rect x="34" y="60" width="32" height="10" rx="4" fill="none" stroke="#22b7ff" stroke-width="3.5"/>
            <rect x="34" y="74" width="32" height="10" rx="4" fill="none" stroke="#22b7ff" stroke-width="3.5"/>
          </svg>
        </div>
      </div>
      <div class="label">Spine protects<br>Spinal Cord</div>
      <div class="sublabel">Vertebrae Stack</div>
    </div>
  </div>

  <div class="action-prompt">Tap any bone group to highlight protection</div>

  <script>
    let activeIdx = 0;
    const cards = [
      document.getElementById('card-0'),
      document.getElementById('card-1'),
      document.getElementById('card-2')
    ];

    function selectCard(idx) {
      activeIdx = idx;
      cards.forEach((c, i) => {
        if (i === idx) {
          c.classList.add('active');
        } else {
          c.classList.remove('active');
        }
      });
    }

    // Gentle auto-cycle every 3.5 seconds
    let timer = setInterval(() => {
      activeIdx = (activeIdx + 1) % 3;
      selectCard(activeIdx);
    }, 3500);

    // Pause cycling on manual tap
    document.querySelectorAll('.protect-card').forEach(el => {
      el.addEventListener('pointerdown', () => {
        clearInterval(timer);
      });
    });
  </script>
</body>
</html>

The Three Main Functions of the Human Skeleton

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Muscles and Movement</title>
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      width: 100%;
      background: #f8fafc;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-start;
      padding: 10px 12px 14px;
      user-select: none;
      overflow-x: hidden;
    }

    .diagram-area {
      width: 100%;
      max-width: 420px;
      display: flex;
      align-items: center;
      justify-content: center;
      position: relative;
    }

    svg {
      width: 100%;
      height: auto;
      display: block;
    }

    .label-box {
      font-size: 11px;
      font-weight: 700;
      fill: #1e2945;
    }
    .label-sub {
      font-size: 9.5px;
      font-weight: 600;
      fill: #64748b;
    }
    .label-bg {
      fill: #ffffff;
      stroke: #cbd5e1;
      stroke-width: 1;
      rx: 6;
      filter: drop-shadow(0 1px 2px rgba(0,0,0,0.06));
    }

    /* Interactive Controls */
    .controls {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      width: 100%;
      max-width: 380px;
      margin-top: 8px;
    }

    .btn {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      color: #1e2945;
      padding: 6px 14px;
      border-radius: 20px;
      font-size: 12px;
      font-weight: 600;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      box-shadow: 0 1px 2px rgba(0,0,0,0.04);
      transition: background-color 0.2s, border-color 0.2s, color 0.2s;
    }
    .btn:hover {
      background-color: #f1f5f9;
      border-color: #94a3b8;
    }
    .btn.active {
      background-color: #1e2945;
      border-color: #1e2945;
      color: #ffffff;
    }
  </style>
</head>
<body>

  <div class="diagram-area">
    <svg viewBox="0 0 420 270" preserveAspectRatio="xMidYMid meet">
      <defs>
        
        <filter id="soft-shadow" x="-10%" y="-10%" width="120%" height="120%">
          <feDropShadow dx="0" dy="2" stdDeviation="2.5" flood-opacity="0.08" />
        </filter>
        
        <marker id="arrow" viewBox="0 0 10 10" refX="6" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
          <path d="M 0 1.5 L 8 5 L 0 8.5 z" fill="#ef4444" />
        </marker>
        
        <marker id="lift-arrow" viewBox="0 0 10 10" refX="6" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
          <path d="M 0 1.5 L 8 5 L 0 8.5 z" fill="#3b82f6" />
        </marker>
      </defs>

      
      <g id="upper-arm">
        
        <circle cx="150" cy="40" r="18" fill="#e2e8f0" stroke="#cbd5e1" stroke-width="2" />
        
        <rect x="138" y="40" width="24" height="142" rx="12" fill="#e2e8f0" stroke="#cbd5e1" stroke-width="2" />
      </g>

      
      <path id="lever-arc" d="M 280 168 A 130 130 0 0 0 225 78" fill="none" stroke="#3b82f6" stroke-width="2" stroke-dasharray="4 4" marker-end="url(#lift-arrow)" />

      
      <g id="forearm-group" transform="rotate(0, 150, 180)">
        
        <rect x="150" y="168" width="130" height="24" rx="12" fill="#e2e8f0" stroke="#cbd5e1" stroke-width="2" filter="url(#soft-shadow)" />
        
        <circle cx="285" cy="180" r="13" fill="#e2e8f0" stroke="#cbd5e1" stroke-width="2" />
        
        <circle cx="186" cy="172" r="4" fill="#f87171" stroke="#ef4444" stroke-width="1.5" />
      </g>

      
      <g id="elbow-pivot">
        <circle cx="150" cy="180" r="15" fill="#ffffff" stroke="#cbd5e1" stroke-width="2" filter="url(#soft-shadow)" />
        <circle cx="150" cy="180" r="6.5" fill="#1e2945" />
        <circle cx="150" cy="180" r="2" fill="#ffffff" />
      </g>

      
      <path id="bicep-muscle" d="" fill="#ef4444" stroke="#dc2626" stroke-width="1.5" filter="url(#soft-shadow)" />
      
      <path id="tendon-top" d="" stroke="#f8fafc" stroke-width="4" stroke-linecap="round" />
      <path id="tendon-bottom" d="" stroke="#f8fafc" stroke-width="4" stroke-linecap="round" />

      
      <path id="pull-arrow" d="" stroke="#ef4444" stroke-width="2.5" stroke-linecap="round" fill="none" marker-end="url(#arrow)" />

      

      
      <g class="label-group">
        <rect class="label-bg" x="8" y="65" width="132" height="40" />
        <text class="label-box" x="16" y="82">Muscle contracts</text>
        <text class="label-sub" x="16" y="96">(pulls forearm)</text>
        <path id="muscle-pointer-line" d="" stroke="#94a3b8" stroke-width="1.5" stroke-dasharray="2 2" />
        <circle id="muscle-pointer-dot" cx="0" cy="0" r="3.5" fill="#ef4444" stroke="#ffffff" stroke-width="1" />
      </g>

      
      <g class="label-group">
        <rect class="label-bg" x="15" y="218" width="126" height="40" />
        <text class="label-box" x="23" y="235">Joint (elbow pivot)</text>
        <text class="label-sub" x="23" y="249">hinge pivot point</text>
        <path d="M 115 218 L 140 188" stroke="#94a3b8" stroke-width="1.5" stroke-dasharray="2 2" />
        <circle cx="140" cy="188" r="3.5" fill="#1e2945" stroke="#ffffff" stroke-width="1" />
      </g>

      
      <g class="label-group">
        <rect class="label-bg" x="255" y="218" width="145" height="40" />
        <text class="label-box" x="263" y="235">Bone acts as lever</text>
        <text class="label-sub" x="263" y="249">lifts forearm &amp; hand</text>
        <path id="bone-pointer-line" d="" stroke="#94a3b8" stroke-width="1.5" stroke-dasharray="2 2" />
        <circle id="bone-pointer-dot" cx="0" cy="0" r="3.5" fill="#3b82f6" stroke="#ffffff" stroke-width="1" />
      </g>
    </svg>
  </div>

  
  <div class="controls">
    <button class="btn" id="btn-relax">1. Relaxed</button>
    <button class="btn" id="btn-flex">2. Contracted</button>
    <button class="btn active" id="btn-auto">▶ Loop</button>
  </div>

  <script>
    const forearmGroup = document.getElementById('forearm-group');
    const bicepMuscle = document.getElementById('bicep-muscle');
    const tendonTop = document.getElementById('tendon-top');
    const tendonBottom = document.getElementById('tendon-bottom');
    const pullArrow = document.getElementById('pull-arrow');
    const leverArc = document.getElementById('lever-arc');

    const musclePointerLine = document.getElementById('muscle-pointer-line');
    const musclePointerDot = document.getElementById('muscle-pointer-dot');
    const bonePointerLine = document.getElementById('bone-pointer-line');
    const bonePointerDot = document.getElementById('bone-pointer-dot');

    const btnRelax = document.getElementById('btn-relax');
    const btnFlex = document.getElementById('btn-flex');
    const btnAuto = document.getElementById('btn-auto');

    let currentT = 0; // 0 = relaxed, 1 = contracted
    let targetT = 0;
    let isAuto = true;
    let loopTime = 0;

    // Origin near shoulder
    const origin = { x: 145, y: 55 };
    // Pivot at elbow
    const elbow = { x: 150, y: 180 };
    // Insertion offset from elbow on forearm bone
    const insertionDist = 36;
    const insertionOffsetY = -8;
    // Lever indicator target distance along forearm
    const leverIndicatorDist = 80;

    function updateArm(t) {
      // Forearm angle from 0 (horizontal) to -55 degrees (bent up)
      const angleDeg = -55 * t;
      forearmGroup.setAttribute('transform', `rotate(${angleDeg}, ${elbow.x}, ${elbow.y})`);

      // Insertion point in world coordinates
      const rad = (angleDeg * Math.PI) / 180;
      const cosA = Math.cos(rad);
      const sinA = Math.sin(rad);

      const insX = elbow.x + (insertionDist * cosA - insertionOffsetY * sinA);
      const insY = elbow.y + (insertionDist * sinA + insertionOffsetY * cosA);

      // Dynamic pointer attachment on forearm bone for "Bone acts as lever" label
      const boneTargetX = elbow.x + leverIndicatorDist * cosA;
      const boneTargetY = elbow.y + leverIndicatorDist * sinA;
      bonePointerLine.setAttribute('d', `M 285 218 L ${boneTargetX.toFixed(1)} ${boneTargetY.toFixed(1)}`);
      bonePointerDot.setAttribute('cx', boneTargetX.toFixed(1));
      bonePointerDot.setAttribute('cy', boneTargetY.toFixed(1));

      // Midpoint between shoulder origin and insertion
      const midX = (origin.x + insX) / 2;
      const midY = (origin.y + insY) / 2;

      // Muscle belly bulges outward (leftwards) more as it contracts
      const bulge = 16 + t * 22;
      const thickness = 10 + t * 14;

      // Draw muscle belly shape
      const cpxLeft = midX - bulge;
      const cpyLeft = midY;
      const cpxRight = midX - (bulge - thickness * 2);
      const cpyRight = midY;

      const pathData = `
        M ${origin.x} ${origin.y}
        Q ${cpxLeft} ${cpyLeft}, ${insX} ${insY}
        Q ${cpxRight} ${cpyRight}, ${origin.x} ${origin.y}
        Z
      `;
      bicepMuscle.setAttribute('d', pathData);

      // Tendon lines
      tendonTop.setAttribute('d', `M 148 45 L ${origin.x} ${origin.y}`);
      tendonBottom.setAttribute('d', `M ${insX} ${insY} L ${insX + cosA * 4} ${insY + sinA * 4}`);

      // Dynamic pointer to muscle belly
      const muscleTargetX = cpxLeft + 4;
      const muscleTargetY = cpyLeft;
      musclePointerLine.setAttribute('d', `M 125 105 L ${muscleTargetX.toFixed(1)} ${muscleTargetY.toFixed(1)}`);
      musclePointerDot.setAttribute('cx', muscleTargetX.toFixed(1));
      musclePointerDot.setAttribute('cy', muscleTargetY.toFixed(1));

      // Dynamic Pull Arrow along muscle line
      if (t > 0.08) {
        pullArrow.style.opacity = Math.min(1, (t - 0.08) / 0.25);
        const arrowStartDist = 0.72;
        const arrowEndDist = 0.28;
        const ax1 = insX + (origin.x - insX) * arrowStartDist - (10 * t);
        const ay1 = insY + (origin.y - insY) * arrowStartDist;
        const ax2 = insX + (origin.x - insX) * arrowEndDist - (10 * t);
        const ay2 = insY + (origin.y - insY) * arrowEndDist;
        pullArrow.setAttribute('d', `M ${ax1} ${ay1} L ${ax2} ${ay2}`);
      } else {
        pullArrow.style.opacity = '0';
      }

      leverArc.style.opacity = 0.25 + t * 0.75;
    }

    // Animation Loop: 3.2s cycle with smooth ease-in-out and dedicated pause holds
    let lastTime = performance.now();
    function animate(now) {
      const dt = Math.min((now - lastTime) / 1000, 0.1);
      lastTime = now;

      if (isAuto) {
        loopTime += dt;
        const cycle = 3.2;
        const tInCycle = loopTime % cycle;

        if (tInCycle < 0.6) {
          // Pause at fully relaxed (600ms)
          currentT = 0;
        } else if (tInCycle < 1.6) {
          // Smooth flexion phase (1000ms with ease-in-out)
          const p = (tInCycle - 0.6) / 1.0;
          currentT = 0.5 - 0.5 * Math.cos(p * Math.PI);
        } else if (tInCycle < 2.2) {
          // Pause at fully contracted (600ms)
          currentT = 1;
        } else {
          // Smooth relaxation phase (1000ms with ease-in-out)
          const p = (tInCycle - 2.2) / 1.0;
          currentT = 0.5 + 0.5 * Math.cos(p * Math.PI);
        }
      } else {
        // Smooth transition to manual target
        currentT += (targetT - currentT) * Math.min(1, dt * 6);
      }

      updateArm(currentT);
      requestAnimationFrame(animate);
    }
    requestAnimationFrame(animate);

    // Button interactions
    function setActiveBtn(btn) {
      btnRelax.classList.remove('active');
      btnFlex.classList.remove('active');
      btnAuto.classList.remove('active');
      if (btn) btn.classList.add('active');
    }

    btnRelax.addEventListener('click', () => {
      isAuto = false;
      targetT = 0;
      setActiveBtn(btnRelax);
    });

    btnFlex.addEventListener('click', () => {
      isAuto = false;
      targetT = 1;
      setActiveBtn(btnFlex);
    });

    btnAuto.addEventListener('click', () => {
      isAuto = true;
      loopTime = 0;
      setActiveBtn(btnAuto);
    });
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      background-color: #f8fafc;
      color: #1e2945;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 10px;
      padding: 12px;
      user-select: none;
    }

    /* Header Badge */
    .badge {
      background: #e0f2fe;
      color: #0369a1;
      font-size: 13px;
      font-weight: 700;
      padding: 5px 14px;
      border-radius: 20px;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      letter-spacing: 0.2px;
    }

    /* Comparison Grid */
    .comparison-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 10px;
      width: 100%;
      max-width: 520px;
    }

    .panel {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 14px;
      padding: 10px 8px 6px;
      display: flex;
      flex-direction: column;
      align-items: center;
      box-shadow: 0 1px 4px rgba(0, 0, 0, 0.04);
      position: relative;
    }

    .panel-title {
      font-size: 13px;
      font-weight: 700;
      color: #1e2945;
      margin-bottom: 2px;
    }

    .stage {
      width: 100%;
      height: 170px;
      position: relative;
      overflow: hidden;
    }

    svg {
      width: 100%;
      height: 100%;
      display: block;
    }

    /* Animated states */
    .upright-view, .collapsed-view {
      transition: opacity 0.35s ease, transform 0.35s ease;
      transform-origin: bottom center;
    }

    .collapsed-view {
      opacity: 0;
      transform: scaleY(0.3);
      pointer-events: none;
    }

    body.collapsed .upright-view {
      opacity: 0;
      transform: scaleY(0.2) translateY(60px);
    }

    body.collapsed .collapsed-view {
      opacity: 1;
      transform: scaleY(1);
    }

    /* Interactive Toggle */
    .toggle-bar {
      display: flex;
      background: #e2e8f0;
      border-radius: 30px;
      padding: 3px;
      gap: 4px;
    }

    .toggle-btn {
      border: none;
      background: transparent;
      padding: 7px 16px;
      border-radius: 24px;
      font-size: 12px;
      font-weight: 700;
      color: #475569;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 6px;
      transition: background 0.2s ease, color 0.2s ease, box-shadow 0.2s ease;
    }

    .toggle-btn.active {
      background: #0284c7;
      color: #ffffff;
      box-shadow: 0 2px 6px rgba(2, 132, 199, 0.35);
    }

    .toggle-btn:focus-visible {
      outline: 2px solid #0369a1;
    }

    /* Responsive mobile layout */
    @media (max-width: 480px) {
      .comparison-grid {
        grid-template-columns: 1fr;
        max-width: 320px;
      }
      .stage {
        height: 140px;
      }
    }
  </style>
</head>
<body>

  
  <div class="badge">
    <span>🦴</span> Support &amp; Shape
  </div>

  
  <div class="comparison-grid">
    
    
    <div class="panel">
      <span class="panel-title">Tent Poles</span>
      <div class="stage">
        <svg viewBox="0 0 170 190">
          
          <line x1="15" y1="172" x2="155" y2="172" stroke="#cbd5e1" stroke-width="2" stroke-linecap="round"/>

          
          <g class="upright-view">
            
            <polygon points="75,40 22,170 128,170" fill="rgba(34, 183, 255, 0.15)" stroke="#94a3b8" stroke-width="1.5" stroke-dasharray="3,3"/>
            <polygon points="75,40 75,170 128,170" fill="rgba(2, 132, 199, 0.18)"/>
            
            <line x1="75" y1="40" x2="22" y2="170" stroke="#0284c7" stroke-width="3.5" stroke-linecap="round"/>
            <line x1="75" y1="40" x2="128" y2="170" stroke="#0284c7" stroke-width="3.5" stroke-linecap="round"/>
            <line x1="75" y1="40" x2="75" y2="170" stroke="#0369a1" stroke-width="2.5" stroke-linecap="round"/>
            <circle cx="75" cy="40" r="4" fill="#0369a1"/>
            
            
            <line x1="102" y1="95" x2="130" y2="78" stroke="#0369a1" stroke-width="1.5"/>
            <circle cx="102" cy="95" r="2.5" fill="#0369a1"/>
            <text x="132" y="76" font-size="11" font-weight="700" fill="#0369a1" text-anchor="start">Frame</text>
          </g>

          
          <g class="collapsed-view">
            
            <path d="M 22 172 Q 48 152 75 167 Q 102 157 128 172 Z" fill="rgba(148, 163, 184, 0.35)" stroke="#64748b" stroke-width="1.5"/>
            <text x="75" y="142" font-size="11" font-weight="700" fill="#64748b" text-anchor="middle">No Poles</text>
          </g>
        </svg>
      </div>
    </div>

    
    <div class="panel">
      <span class="panel-title">Human Skeleton</span>
      <div class="stage">
        <svg viewBox="0 0 170 190">
          
          <line x1="15" y1="172" x2="155" y2="172" stroke="#cbd5e1" stroke-width="2" stroke-linecap="round"/>

          
          <g class="upright-view">
            
            
            <circle cx="68" cy="32" r="14" fill="rgba(34, 183, 255, 0.12)" stroke="#94a3b8" stroke-width="1.2"/>
            
            <path d="M 57 46 Q 53 78 57 108 L 79 108 Q 83 78 79 46 Z" fill="rgba(34, 183, 255, 0.12)" stroke="#94a3b8" stroke-width="1.2"/>
            
            <path d="M 56 48 Q 44 78 42 108" fill="none" stroke="#94a3b8" stroke-width="5" stroke-linecap="round" opacity="0.3"/>
            <path d="M 80 48 Q 92 78 94 108" fill="none" stroke="#94a3b8" stroke-width="5" stroke-linecap="round" opacity="0.3"/>
            
            <path d="M 61 108 L 57 170" stroke="#94a3b8" stroke-width="7" stroke-linecap="round" opacity="0.25"/>
            <path d="M 75 108 L 79 170" stroke="#94a3b8" stroke-width="7" stroke-linecap="round" opacity="0.25"/>

            
            
            <circle cx="68" cy="32" r="7" fill="#ffffff" stroke="#0284c7" stroke-width="2"/>
            
            <line x1="68" y1="44" x2="68" y2="105" stroke="#0284c7" stroke-width="3.5" stroke-linecap="round"/>
            
            <line x1="61" y1="58" x2="75" y2="58" stroke="#0369a1" stroke-width="2" stroke-linecap="round"/>
            <line x1="59" y1="68" x2="77" y2="68" stroke="#0369a1" stroke-width="2" stroke-linecap="round"/>
            <line x1="62" y1="78" x2="74" y2="78" stroke="#0369a1" stroke-width="2" stroke-linecap="round"/>
            
            <ellipse cx="68" cy="105" rx="10" ry="4.5" fill="#ffffff" stroke="#0284c7" stroke-width="2"/>
            
            <line x1="62" y1="108" x2="57" y2="170" stroke="#0284c7" stroke-width="3" stroke-linecap="round"/>
            <line x1="74" y1="108" x2="79" y2="170" stroke="#0284c7" stroke-width="3" stroke-linecap="round"/>

            
            <line x1="68" y1="68" x2="114" y2="68" stroke="#0369a1" stroke-width="1.5"/>
            <circle cx="68" cy="68" r="2.5" fill="#0369a1"/>
            <text x="118" y="72" font-size="11" font-weight="700" fill="#0369a1" text-anchor="start">Spine</text>

            <line x1="78" y1="138" x2="114" y2="138" stroke="#0369a1" stroke-width="1.5"/>
            <circle cx="78" cy="138" r="2.5" fill="#0369a1"/>
            <text x="118" y="142" font-size="11" font-weight="700" fill="#0369a1" text-anchor="start">Legs</text>
          </g>

          
          <g class="collapsed-view">
            <ellipse cx="68" cy="168" rx="42" ry="11" fill="rgba(34, 183, 255, 0.25)" stroke="#64748b" stroke-width="1.5"/>
            <text x="68" y="142" font-size="11" font-weight="700" fill="#64748b" text-anchor="middle">No Bones</text>
          </g>
        </svg>
      </div>
    </div>

  </div>

  
  <div class="toggle-bar">
    <button id="btnWith" class="toggle-btn active" onclick="setSupport(true)">
      <span>✓</span> With Framework
    </button>
    <button id="btnWithout" class="toggle-btn" onclick="setSupport(false)">
      <span>✕</span> Without
    </button>
  </div>

  <script>
    function setSupport(hasBones) {
      const body = document.body;
      const btnWith = document.getElementById('btnWith');
      const btnWithout = document.getElementById('btnWithout');

      if (hasBones) {
        body.classList.remove('collapsed');
        btnWith.classList.add('active');
        btnWithout.classList.remove('active');
      } else {
        body.classList.add('collapsed');
        btnWith.classList.remove('active');
        btnWithout.classList.add('active');
      }
    }
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <title>Ball-and-Socket Joint</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      color: #1e2945;
      background: #ffffff;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      padding: 12px;
      min-height: 100%;
      user-select: none;
    }

    .header-badge {
      background: #eff6ff;
      border: 1px solid #bfdbfe;
      color: #1d4ed8;
      font-size: 14px;
      font-weight: 700;
      padding: 6px 14px;
      border-radius: 20px;
      text-align: center;
      letter-spacing: -0.2px;
    }

    .panels-container {
      display: flex;
      flex-direction: row;
      justify-content: center;
      align-items: center;
      gap: 12px;
      width: 100%;
      max-width: 600px;
      margin: 8px 0;
    }

    .panel {
      flex: 1;
      min-width: 150px;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      position: relative;
    }

    .panel-title {
      font-size: 13px;
      font-weight: 700;
      color: #475569;
      margin-bottom: 4px;
      text-transform: uppercase;
      letter-spacing: 0.5px;
    }

    .joint-svg {
      width: 100%;
      max-width: 220px;
      height: 200px;
      overflow: visible;
    }

    /* Motion Controls */
    .controls {
      display: flex;
      gap: 8px;
      flex-wrap: wrap;
      justify-content: center;
    }

    .btn {
      appearance: none;
      border: 1px solid #cbd5e1;
      background: #ffffff;
      color: #334155;
      padding: 6px 12px;
      border-radius: 8px;
      font-size: 13px;
      font-weight: 600;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 4px;
      transition: all 0.2s ease;
    }

    .btn:active {
      transform: translateY(1px);
    }

    .btn.active {
      background: #2563eb;
      color: #ffffff;
      border-color: #2563eb;
      box-shadow: 0 2px 6px rgba(37, 99, 235, 0.25);
    }

    /* Rotating Bone Animations */
    .mech-ball-shaft, .bio-humerus {
      transform-origin: 100px 88px;
      transition: transform 0.5s ease-out;
    }

    /* Default 360 Full Cone Orbit */
    .mode-all .mech-ball-shaft,
    .mode-all .bio-humerus {
      animation: orbitAll 4s ease-in-out infinite;
    }

    /* Up-Down Pitch Motion */
    .mode-updown .mech-ball-shaft,
    .mode-updown .bio-humerus {
      animation: moveUpDown 3s ease-in-out infinite;
    }

    /* Side-to-Side Yaw Motion */
    .mode-sideside .mech-ball-shaft,
    .mode-sideside .bio-humerus {
      animation: moveSideSide 3s ease-in-out infinite;
    }

    /* Rotation Ring Animations */
    .rot-ring {
      transform-origin: 100px 88px;
      transition: opacity 0.3s ease;
    }

    .mode-all .ring-yaw,
    .mode-all .ring-pitch,
    .mode-all .ring-roll {
      opacity: 0.9;
    }

    .mode-updown .ring-yaw,
    .mode-updown .ring-roll {
      opacity: 0.15;
    }
    .mode-updown .ring-pitch {
      opacity: 1;
    }

    .mode-sideside .ring-pitch,
    .mode-sideside .ring-roll {
      opacity: 0.15;
    }
    .mode-sideside .ring-yaw {
      opacity: 1;
    }

    @keyframes orbitAll {
      0% {
        transform: rotate(0deg) translate(0, 0);
      }
      25% {
        transform: rotate(18deg) scaleY(0.95);
      }
      50% {
        transform: rotate(-14deg) scaleY(1.05);
      }
      75% {
        transform: rotate(-20deg) scaleX(0.95);
      }
      100% {
        transform: rotate(0deg) translate(0, 0);
      }
    }

    @keyframes moveUpDown {
      0%, 100% {
        transform: rotate(0deg) scaleY(1);
      }
      50% {
        transform: rotate(24deg) scaleY(0.9);
      }
    }

    @keyframes moveSideSide {
      0%, 100% {
        transform: rotate(-22deg);
      }
      50% {
        transform: rotate(22deg);
      }
    }

    /* Swirling arrow pulse */
    .swirl-arrow {
      animation: dashPulse 2.5s linear infinite;
    }
    @keyframes dashPulse {
      to {
        stroke-dashoffset: -32;
      }
    }
  </style>
</head>
<body>

  
  <div class="header-badge">
    Movement: All Directions (Maximum Freedom)
  </div>

  
  <div class="panels-container mode-all" id="panelsWrap">
    
    
    <div class="panel">
      <div class="panel-title">Mechanical Model</div>
      <svg class="joint-svg" viewBox="0 0 200 200">
        <defs>
          
          <radialGradient id="ballGrad" cx="35%" cy="30%" r="65%">
            <stop offset="0%" stop-color="#93c5fd" />
            <stop offset="45%" stop-color="#3b82f6" />
            <stop offset="90%" stop-color="#1d4ed8" />
            <stop offset="100%" stop-color="#1e3a8a" />
          </radialGradient>

          <radialGradient id="cupInnerGrad" cx="50%" cy="50%" r="50%">
            <stop offset="60%" stop-color="#cbd5e1" />
            <stop offset="95%" stop-color="#64748b" />
            <stop offset="100%" stop-color="#475569" />
          </radialGradient>

          <linearGradient id="cupOuterGrad" x1="0" y1="0" x2="1" y2="1">
            <stop offset="0%" stop-color="#f1f5f9" />
            <stop offset="100%" stop-color="#94a3b8" />
          </linearGradient>

          <linearGradient id="shaftGrad" x1="0" y1="0" x2="1" y2="0">
            <stop offset="0%" stop-color="#60a5fa" />
            <stop offset="50%" stop-color="#93c5fd" />
            <stop offset="100%" stop-color="#2563eb" />
          </linearGradient>

          
          <marker id="arrBlue" markerWidth="6" markerHeight="6" refX="4" refY="3" orient="auto">
            <polygon points="0 0, 6 3, 0 6" fill="#0284c7" />
          </marker>
          <marker id="arrAmber" markerWidth="6" markerHeight="6" refX="4" refY="3" orient="auto">
            <polygon points="0 0, 6 3, 0 6" fill="#d97706" />
          </marker>
        </defs>

        
        <g class="rot-ring ring-pitch">
          <ellipse cx="100" cy="140" rx="42" ry="12" fill="none" stroke="#d97706" stroke-width="2.5" stroke-dasharray="4 3" class="swirl-arrow" />
        </g>
        <g class="rot-ring ring-yaw">
          <path d="M 60 148 Q 100 168 140 148" fill="none" stroke="#0284c7" stroke-width="2.5" marker-end="url(#arrBlue)" />
          <path d="M 140 148 Q 100 128 60 148" fill="none" stroke="#0284c7" stroke-width="2.5" marker-end="url(#arrBlue)" />
        </g>

        
        <path d="M 62 48 C 62 25 138 25 138 48 C 138 68 128 92 100 92 C 72 92 62 68 62 48 Z" fill="url(#cupOuterGrad)" stroke="#64748b" stroke-width="2" />
        <ellipse cx="100" cy="50" rx="38" ry="18" fill="url(#cupInnerGrad)" stroke="#475569" stroke-width="1.5" />

        
        <g class="mech-ball-shaft">
          
          <rect x="92" y="88" width="16" height="78" rx="8" fill="url(#shaftGrad)" stroke="#1d4ed8" stroke-width="1.5" />
          <circle cx="100" cy="166" r="11" fill="#3b82f6" stroke="#1d4ed8" stroke-width="1.5" />

          
          <circle cx="100" cy="80" r="26" fill="url(#ballGrad)" stroke="#1e3a8a" stroke-width="1.5" />
          
          <ellipse cx="92" cy="72" rx="7" ry="4" fill="#ffffff" opacity="0.6" transform="rotate(-20 92 72)" />
        </g>

        
        <path d="M 64 52 C 64 78 80 94 100 94 C 120 94 136 78 136 52 C 128 68 116 76 100 76 C 84 76 72 68 64 52 Z" fill="#64748b" opacity="0.4" />
      </svg>
    </div>

    
    <div class="panel">
      <div class="panel-title">Shoulder Joint</div>
      <svg class="joint-svg" viewBox="0 0 200 200">
        <defs>
          
          <radialGradient id="boneHeadGrad" cx="35%" cy="30%" r="65%">
            <stop offset="0%" stop-color="#ffffff" />
            <stop offset="50%" stop-color="#fed7aa" />
            <stop offset="85%" stop-color="#f97316" />
            <stop offset="100%" stop-color="#c2410c" />
          </radialGradient>

          <linearGradient id="boneShaftGrad" x1="0" y1="0" x2="1" y2="0">
            <stop offset="0%" stop-color="#ffedd5" />
            <stop offset="50%" stop-color="#ffedd5" />
            <stop offset="100%" stop-color="#fdba74" />
          </linearGradient>

          <linearGradient id="scapulaGrad" x1="0" y1="0" x2="1" y2="1">
            <stop offset="0%" stop-color="#f8fafc" />
            <stop offset="50%" stop-color="#e2e8f0" />
            <stop offset="100%" stop-color="#94a3b8" />
          </linearGradient>
        </defs>

        
        <g class="rot-ring ring-pitch">
          <ellipse cx="100" cy="140" rx="42" ry="12" fill="none" stroke="#d97706" stroke-width="2.5" stroke-dasharray="4 3" class="swirl-arrow" />
        </g>
        <g class="rot-ring ring-yaw">
          <path d="M 60 148 Q 100 168 140 148" fill="none" stroke="#0284c7" stroke-width="2.5" marker-end="url(#arrBlue)" />
          <path d="M 140 148 Q 100 128 60 148" fill="none" stroke="#0284c7" stroke-width="2.5" marker-end="url(#arrBlue)" />
        </g>

        
        
        <path d="M 40 32 Q 90 28 115 42 Q 95 50 65 42 Z" fill="url(#scapulaGrad)" stroke="#64748b" stroke-width="1.5" />
        <path d="M 50 40 Q 68 50 72 88 Q 50 75 42 55 Z" fill="url(#scapulaGrad)" stroke="#64748b" stroke-width="1.5" />
        
        
        <path d="M 68 56 C 68 40 126 40 126 56 C 126 80 114 96 97 96 C 80 96 68 80 68 56 Z" fill="#cbd5e1" stroke="#64748b" stroke-width="1.5" />
        <ellipse cx="97" cy="58" rx="27" ry="14" fill="#94a3b8" stroke="#475569" stroke-width="1" />

        
        <g class="bio-humerus">
          
          <path d="M 90 92 L 88 165 C 88 172 106 172 106 165 L 104 92 Z" fill="url(#boneShaftGrad)" stroke="#ea580c" stroke-width="1.5" />
          
          
          <circle cx="97" cy="80" r="23" fill="url(#boneHeadGrad)" stroke="#c2410c" stroke-width="1.5" />
          
          
          <ellipse cx="90" cy="74" rx="6" ry="3" fill="#ffffff" opacity="0.65" transform="rotate(-25 90 74)" />
        </g>

        
        <path d="M 72 62 C 74 80 84 94 97 94 C 110 94 120 80 122 62 C 114 74 106 80 97 80 C 88 80 80 74 72 62 Z" fill="#64748b" opacity="0.45" />
      </svg>
    </div>

  </div>

  
  <div class="controls">
    <button class="btn active" data-mode="mode-all">🔄 360° All Directions</button>
    <button class="btn" data-mode="mode-updown">↕ Up & Down</button>
    <button class="btn" data-mode="mode-sideside">↔ Side to Side</button>
  </div>

  <script>
    const wrap = document.getElementById('panelsWrap');
    const buttons = document.querySelectorAll('.btn');

    buttons.forEach(btn => {
      btn.addEventListener('click', () => {
        buttons.forEach(b => b.classList.remove('active'));
        btn.classList.add('active');

        wrap.className = 'panels-container ' + btn.dataset.mode;
      });
    });
  </script>
</body>
</html>

Types of Joints: Hinge, Ball-and-Socket, and Fixed

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Joint Types by Range of Movement</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    }

    body {
      background: transparent;
      color: #0f172a;
      padding: 8px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-start;
      min-height: auto;
      width: 100%;
    }

    .grid-container {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 12px;
      width: 100%;
      max-width: 680px;
    }

    .joint-card {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 12px 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      box-shadow: 0 2px 5px rgba(0, 0, 0, 0.05);
    }

    .badge {
      font-size: 11px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.5px;
      padding: 3px 10px;
      border-radius: 20px;
      margin-bottom: 6px;
      display: inline-block;
    }

    .badge-fixed { background: #f1f5f9; color: #475569; border: 1px solid #cbd5e1; }
    .badge-hinge { background: #e0f2fe; color: #0284c7; border: 1px solid #bae6fd; }
    .badge-ball { background: #dcfce7; color: #15803d; border: 1px solid #bbf7d0; }

    .card-title {
      font-size: 15px;
      font-weight: 700;
      color: #0f172a;
      line-height: 1.25;
    }

    .card-subtitle {
      font-size: 12px;
      color: #64748b;
      margin-top: 2px;
      margin-bottom: 6px;
    }

    .stage {
      width: 100%;
      height: 120px;
      display: flex;
      align-items: center;
      justify-content: center;
      position: relative;
      margin: 4px 0;
    }

    svg {
      width: 100%;
      height: 100%;
      max-height: 120px;
      overflow: visible;
    }

    .range-label {
      font-size: 12px;
      font-weight: 700;
      margin-top: 6px;
      padding: 6px 8px;
      border-radius: 8px;
      width: 100%;
      text-align: center;
    }

    .range-fixed { color: #334155; background: #f1f5f9; }
    .range-hinge { color: #0369a1; background: #e0f2fe; }
    .range-ball { color: #15803d; background: #dcfce7; }

    /* Motion Animations: slow, clear cycles with >500ms holds */
    .hinge-arm {
      transform-origin: 50px 82px;
      animation: swingArm 5s ease-in-out infinite;
    }

    .hinge-arc {
      stroke-dasharray: 65;
      stroke-dashoffset: 65;
      animation: drawArc 5s ease-in-out infinite;
    }

    @keyframes swingArm {
      0%, 20% {
        transform: rotate(0deg);
      }
      45%, 70% {
        transform: rotate(-72deg);
      }
      90%, 100% {
        transform: rotate(0deg);
      }
    }

    @keyframes drawArc {
      0%, 15% {
        stroke-dashoffset: 65;
        opacity: 0.3;
      }
      45%, 70% {
        stroke-dashoffset: 0;
        opacity: 1;
      }
      90%, 100% {
        stroke-dashoffset: 65;
        opacity: 0.3;
      }
    }

    .orbit-ring {
      transform-origin: 50px 52px;
      animation: rotateOrbit 8s linear infinite;
    }

    .ball-stem-group {
      transform-origin: 50px 52px;
      animation: ballSway 6s ease-in-out infinite;
    }

    @keyframes rotateOrbit {
      0% {
        transform: rotate(0deg);
      }
      100% {
        transform: rotate(360deg);
      }
    }

    @keyframes ballSway {
      0%, 15% {
        transform: rotate(0deg);
      }
      35%, 50% {
        transform: rotate(24deg);
      }
      65%, 80% {
        transform: rotate(-24deg);
      }
      95%, 100% {
        transform: rotate(0deg);
      }
    }

    /* Responsive adjustments for mobile / narrow viewports */
    @media (max-width: 499px) {
      .grid-container {
        grid-template-columns: 1fr;
        max-width: 360px;
        gap: 10px;
      }

      .joint-card {
        padding: 10px 12px;
      }

      .stage {
        height: 100px;
      }

      svg {
        max-height: 100px;
      }
    }
  </style>
</head>
<body>

  <div class="grid-container">

    
    <div class="joint-card">
      <span class="badge badge-fixed">Protection</span>
      <div class="card-title">Fixed Joint</div>
      <div class="card-subtitle">Skull (Cranium)</div>

      <div class="stage">
        <svg viewBox="0 0 100 105" aria-label="Fixed Joint Diagram">
          
          <path d="M 22 80 C 16 42 30 18 50 18 C 70 18 84 42 78 80 Z" fill="#f8fafc" stroke="#94a3b8" stroke-width="2.5" />
          
          
          <path d="M 50 18 L 52 28 L 47 35 L 53 43 L 47 51 L 53 59 L 48 68 L 50 80" fill="none" stroke="#475569" stroke-width="2.5" stroke-linejoin="round" stroke-linecap="round" />
          <path d="M 32 45 L 40 47 L 47 51" fill="none" stroke="#64748b" stroke-width="1.8" stroke-linejoin="round" />
          <path d="M 68 45 L 60 47 L 53 51" fill="none" stroke="#64748b" stroke-width="1.8" stroke-linejoin="round" />

          
          <circle cx="34" cy="32" r="2.5" fill="#94a3b8" />
          <circle cx="66" cy="32" r="2.5" fill="#94a3b8" />

          
          <g transform="translate(42, 82)">
            <rect x="2" y="5" width="12" height="10" rx="2" fill="#475569" />
            <path d="M 4 5 L 4 3 C 4 1 12 1 12 3 L 12 5" fill="none" stroke="#475569" stroke-width="2" />
          </g>
        </svg>
      </div>

      <div class="range-label range-fixed">No Movement (0°)</div>
    </div>

    
    <div class="joint-card">
      <span class="badge badge-hinge">Bending</span>
      <div class="card-title">Hinge Joint</div>
      <div class="card-subtitle">Elbow & Knee</div>

      <div class="stage">
        <svg viewBox="0 0 100 105" aria-label="Hinge Joint Diagram">
          
          <rect x="44" y="80" width="12" height="22" rx="4" fill="#cbd5e1" stroke="#94a3b8" stroke-width="1" />

          
          <path class="hinge-arc" d="M 50 28 A 54 54 0 0 0 13 62" fill="none" stroke="#0284c7" stroke-width="2.5" stroke-dasharray="4 3" stroke-linecap="round" />
          <polygon points="10,56 12,66 20,62" fill="#0284c7" />

          
          <circle cx="50" cy="82" r="9" fill="#0284c7" opacity="0.18" />
          <circle cx="50" cy="82" r="5" fill="#0284c7" />

          
          <g class="hinge-arm">
            <rect x="44" y="24" width="12" height="58" rx="5" fill="#38bdf8" stroke="#0284c7" stroke-width="2" />
            <circle cx="50" cy="30" r="3" fill="#ffffff" />
          </g>
        </svg>
      </div>

      <div class="range-label range-hinge">1 Plane Movement</div>
    </div>

    
    <div class="joint-card">
      <span class="badge badge-ball">Full Rotation</span>
      <div class="card-title">Ball & Socket</div>
      <div class="card-subtitle">Shoulder & Hip</div>

      <div class="stage">
        <svg viewBox="0 0 100 105" aria-label="Ball and Socket Joint Diagram">
          
          <rect x="45" y="66" width="10" height="34" rx="3" fill="#cbd5e1" stroke="#94a3b8" stroke-width="1" />

          
          <path d="M 26 44 C 26 70 74 70 74 44" fill="none" stroke="#15803d" stroke-width="4.5" stroke-linecap="round" />

          
          <g class="orbit-ring">
            <ellipse cx="50" cy="52" rx="36" ry="14" fill="none" stroke="#16a34a" stroke-width="1.8" stroke-dasharray="4 3" opacity="0.8" />
            <polygon points="86,52 82,47 82,57" fill="#15803d" />
          </g>

          
          <g class="ball-stem-group">
            <line x1="50" y1="16" x2="50" y2="44" stroke="#16a34a" stroke-width="9" stroke-linecap="round" />
            <circle cx="50" cy="46" r="14" fill="#22c55e" stroke="#15803d" stroke-width="2" />
            <circle cx="45" cy="42" r="3.5" fill="#ffffff" opacity="0.7" />
          </g>

          
          <text x="50" y="13" text-anchor="middle" font-size="10" font-weight="bold" fill="#15803d">360°</text>
        </svg>
      </div>

      <div class="range-label range-ball">All Directions (360°)</div>
    </div>

  </div>

</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      background: #f8fafc;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
      padding: 12px;
      user-select: none;
    }

    .header-badge {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      background: #fef3c7;
      border: 1px solid #fde68a;
      color: #92400e;
      font-size: 13px;
      font-weight: 700;
      padding: 6px 14px;
      border-radius: 999px;
      text-align: center;
    }

    .panels {
      display: flex;
      flex-direction: row;
      gap: 12px;
      width: 100%;
      max-width: 600px;
      justify-content: center;
      margin: 8px 0;
    }

    .panel {
      flex: 1;
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      min-width: 0;
    }

    .panel-title {
      font-size: 14px;
      font-weight: 700;
      color: #334155;
      margin-bottom: 4px;
    }

    svg {
      width: 100%;
      height: auto;
      max-height: 220px;
      overflow: visible;
    }

    .controls {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 8px;
      width: 100%;
      max-width: 420px;
    }

    .btn-group {
      display: flex;
      gap: 8px;
      width: 100%;
      justify-content: center;
    }

    .btn {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      color: #334155;
      padding: 6px 16px;
      font-size: 13px;
      font-weight: 600;
      border-radius: 8px;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      box-shadow: 0 1px 2px rgba(0,0,0,0.05);
    }
    .btn:active {
      background: #f1f5f9;
    }
    .btn.active {
      background: #0284c7;
      border-color: #0284c7;
      color: #ffffff;
    }

    .slider-wrap {
      display: flex;
      align-items: center;
      gap: 10px;
      width: 100%;
    }

    input[type=range] {
      flex: 1;
      accent-color: #0284c7;
      cursor: pointer;
      height: 6px;
    }

    .legend {
      display: flex;
      gap: 12px;
      font-size: 11px;
      color: #64748b;
      font-weight: 600;
      margin-top: 2px;
    }

    .legend-item {
      display: flex;
      align-items: center;
      gap: 4px;
    }

    .legend-dot {
      width: 8px;
      height: 8px;
      border-radius: 50%;
    }
  </style>
</head>
<body>

  <div class="header-badge">
    <span>Movement: 1 Direction (Back and Forth)</span>
  </div>

  <div class="panels">
    
    <div class="panel">
      <div class="panel-title">Door Hinge</div>
      <svg viewBox="0 0 160 180">
        <defs>
          <marker id="arrow-door" viewBox="0 0 10 10" refX="6" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
            <path d="M 0 1 L 10 5 L 0 9 z" fill="#f59e0b"/>
          </marker>
        </defs>

        
        <rect x="20" y="30" width="22" height="120" rx="4" fill="#e2e8f0" stroke="#94a3b8" stroke-width="2"/>
        <text x="31" y="95" font-size="10" font-weight="700" fill="#64748b" text-anchor="middle" transform="rotate(-90 31 95)">FRAME</text>

        
        <path d="M 130 90 A 90 90 0 0 1 70 168" fill="none" stroke="#f59e0b" stroke-width="2.5" stroke-dasharray="4 3" marker-end="url(#arrow-door)"/>

        
        <g id="door-group" transform="rotate(0 40 90)">
          
          <rect x="40" y="83" width="90" height="14" rx="3" fill="#f3f4f6" stroke="#94a3b8" stroke-width="2"/>
          
          <circle cx="118" cy="90" r="3.5" fill="#64748b"/>
        </g>

        
        <circle cx="40" cy="90" r="7.5" fill="#0284c7" stroke="#ffffff" stroke-width="2"/>
        <circle cx="40" cy="90" r="3" fill="#ffffff"/>
      </svg>
    </div>

    
    <div class="panel">
      <div class="panel-title">Elbow Joint</div>
      <svg viewBox="0 0 160 180">
        <defs>
          <marker id="arrow-arm" viewBox="0 0 10 10" refX="6" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
            <path d="M 0 1 L 10 5 L 0 9 z" fill="#f59e0b"/>
          </marker>
        </defs>

        
        <g id="upper-arm">
          <rect x="73" y="16" width="14" height="74" rx="6" fill="#f3f4f6" stroke="#94a3b8" stroke-width="2"/>
          <text x="80" y="55" font-size="9" font-weight="700" fill="#64748b" text-anchor="middle">HUMERUS</text>
        </g>

        
        <path d="M 80 165 A 75 75 0 0 0 145 90" fill="none" stroke="#f59e0b" stroke-width="2.5" stroke-dasharray="4 3" marker-end="url(#arrow-arm)"/>

        
        <g id="forearm-group" transform="rotate(0 80 90)">
          
          <rect x="73" y="90" width="14" height="75" rx="6" fill="#f3f4f6" stroke="#94a3b8" stroke-width="2"/>
          
          <ellipse cx="80" cy="168" rx="6" ry="8" fill="#f3f4f6" stroke="#94a3b8" stroke-width="1.5"/>
          <text x="80" y="132" font-size="9" font-weight="700" fill="#64748b" text-anchor="middle">FOREARM</text>
        </g>

        
        <circle cx="80" cy="90" r="7.5" fill="#0284c7" stroke="#ffffff" stroke-width="2"/>
        <circle cx="80" cy="90" r="3" fill="#ffffff"/>
      </svg>
    </div>
  </div>

  
  <div class="controls">
    <div class="slider-wrap">
      <span style="font-size:12px; font-weight:700; color:#64748b;">Straight</span>
      <input type="range" id="angleSlider" min="0" max="95" value="0" aria-label="Joint Angle">
      <span style="font-size:12px; font-weight:700; color:#64748b;">Bent</span>
    </div>

    <div class="btn-group">
      <button class="btn active" id="btnAuto">⏸ Pause</button>
      <button class="btn" id="btnToggle">Bend / Straighten</button>
    </div>

    <div class="legend">
      <div class="legend-item"><span class="legend-dot" style="background:#0284c7;"></span> Joint Pivot</div>
      <div class="legend-item"><span class="legend-dot" style="background:#f59e0b;"></span> 1D Motion Arc</div>
    </div>
  </div>

  <script>
    const slider = document.getElementById('angleSlider');
    const doorGroup = document.getElementById('door-group');
    const forearmGroup = document.getElementById('forearm-group');
    const btnAuto = document.getElementById('btnAuto');
    const btnToggle = document.getElementById('btnToggle');

    let angle = 0;
    let autoPlaying = true;
    let direction = 1;

    function updateAngle(val) {
      angle = Number(val);
      slider.value = angle;
      // Rotate door: 0 to 95 degrees
      doorGroup.setAttribute('transform', `rotate(${angle} 40 90)`);
      // Rotate forearm: 0 to -95 degrees (bends upwards to right)
      forearmGroup.setAttribute('transform', `rotate(${-angle} 80 90)`);
    }

    slider.addEventListener('input', (e) => {
      if (autoPlaying) toggleAuto();
      updateAngle(e.target.value);
    });

    btnToggle.addEventListener('click', () => {
      if (autoPlaying) toggleAuto();
      const target = angle > 45 ? 0 : 95;
      smoothTransitionTo(target);
    });

    function smoothTransitionTo(target) {
      const step = target > angle ? 3 : -3;
      const anim = setInterval(() => {
        if ((step > 0 && angle >= target) || (step < 0 && angle <= target)) {
          updateAngle(target);
          clearInterval(anim);
        } else {
          updateAngle(angle + step);
        }
      }, 16);
    }

    function toggleAuto() {
      autoPlaying = !autoPlaying;
      if (autoPlaying) {
        btnAuto.textContent = '⏸ Pause';
        btnAuto.classList.add('active');
      } else {
        btnAuto.textContent = '▶ Auto Play';
        btnAuto.classList.remove('active');
      }
    }

    btnAuto.addEventListener('click', toggleAuto);

    // Auto-loop oscillation
    setInterval(() => {
      if (!autoPlaying) return;
      angle += direction * 0.9;
      if (angle >= 95) {
        angle = 95;
        direction = -1;
      } else if (angle <= 0) {
        angle = 0;
        direction = 1;
      }
      updateAngle(angle);
    }, 20);
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      background: transparent;
      padding: 12px;
      display: flex;
      flex-direction: column;
      gap: 12px;
      user-select: none;
    }

    /* Tabs */
    .tab-bar {
      display: flex;
      justify-content: center;
      gap: 8px;
    }

    .tab-btn {
      background: #ffffff;
      border: 1.5px solid #e6e6e6;
      border-radius: 20px;
      padding: 6px 14px;
      font-size: 13px;
      font-weight: 600;
      color: #1e2945;
      cursor: pointer;
      box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
      transition: background 0.2s, color 0.2s, box-shadow 0.2s;
    }

    .tab-btn.active {
      background: #2ecc71;
      border-color: #2ecc71;
      color: #ffffff;
      box-shadow: 0 2px 6px rgba(46, 204, 113, 0.3);
    }

    /* Grid Layout */
    .comparison-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 12px;
      width: 100%;
    }

    @media (max-width: 480px) {
      .comparison-grid {
        grid-template-columns: 1fr;
      }
    }

    /* Inner Column Cards */
    .side-card {
      background: #ffffff;
      border: 1px solid #e6e6e6;
      border-radius: 14px;
      padding: 12px 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
      transition: opacity 0.3s ease, transform 0.3s ease;
      position: relative;
    }

    .side-card.dimmed {
      opacity: 0.35;
    }

    .side-title {
      font-size: 15px;
      font-weight: 700;
      text-align: center;
      margin-bottom: 8px;
    }

    .side-title.plants {
      color: #27ae60;
    }

    .side-title.animals {
      color: #d35400;
    }

    /* Plant Visual Scene */
    .plant-scene {
      width: 100%;
      height: 190px;
      position: relative;
      background: #f4fbf7;
      border-radius: 10px;
      border: 1px dashed #c8eed6;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-end;
      overflow: hidden;
      padding-bottom: 8px;
    }

    .sun-source {
      position: absolute;
      top: 10px;
      left: 14px;
      font-size: 28px;
      display: flex;
      flex-direction: column;
      align-items: center;
    }

    .source-label {
      font-size: 11px;
      font-weight: 700;
      color: #f39c12;
      margin-top: 1px;
    }

    .water-source {
      position: absolute;
      bottom: 24px;
      left: 14px;
      font-size: 22px;
      display: flex;
      flex-direction: column;
      align-items: center;
    }

    .water-label {
      font-size: 11px;
      font-weight: 700;
      color: #2980b9;
      margin-top: 1px;
    }

    .plant-center {
      font-size: 56px;
      line-height: 1;
      margin-bottom: 2px;
      filter: drop-shadow(0 2px 4px rgba(0,0,0,0.1));
    }

    .soil-ground {
      width: 90%;
      height: 8px;
      background: #d7ccc8;
      border-radius: 4px;
    }

    /* Arrows SVG overlay */
    .flow-svg {
      position: absolute;
      inset: 0;
      width: 100%;
      height: 100%;
      pointer-events: none;
    }

    .flow-arrow {
      stroke-dasharray: 4, 3;
      animation: flowDash 1.5s linear infinite;
    }

    @keyframes flowDash {
      to {
        stroke-dashoffset: -14;
      }
    }

    /* Animal Visual Scene */
    .animal-scene {
      width: 100%;
      height: 190px;
      background: #fffaf5;
      border-radius: 10px;
      border: 1px dashed #fcdcc5;
      display: flex;
      flex-direction: column;
      justify-content: space-evenly;
      align-items: center;
      padding: 6px 8px;
    }

    .eat-row {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 90%;
      background: #ffffff;
      padding: 6px 12px;
      border-radius: 8px;
      border: 1px solid #f0ebe4;
    }

    .actor {
      font-size: 30px;
      line-height: 1;
    }

    .action-arrow {
      font-size: 18px;
      font-weight: bold;
      color: #e67e22;
    }

    /* Bottom Badge */
    .bottom-badge {
      margin-top: 10px;
      font-size: 12px;
      font-weight: 700;
      padding: 5px 12px;
      border-radius: 20px;
      text-align: center;
    }

    .badge-plant {
      background: #e8f8ef;
      color: #1e824c;
      border: 1px solid #a3e4d7;
    }

    .badge-animal {
      background: #fdf2e9;
      color: #b9530e;
      border: 1px solid #fad7a0;
    }
  </style>
</head>
<body>

  
  <div class="tab-bar">
    <button class="tab-btn active" id="tabBoth" onclick="setView('both')">Compare Both</button>
    <button class="tab-btn" id="tabPlants" onclick="setView('plants')">Plants 🌻</button>
    <button class="tab-btn" id="tabAnimals" onclick="setView('animals')">Animals 🐇</button>
  </div>

  
  <div class="comparison-grid">
    
    
    <div class="side-card" id="cardPlants">
      <div class="side-title plants">Plants: Food Makers</div>
      <div class="plant-scene">
        
        <svg class="flow-svg" viewBox="0 0 200 180">
          <defs>
            <marker id="arrow-sun" markerWidth="6" markerHeight="6" refX="4" refY="3" orient="auto">
              <polygon points="0 0, 6 3, 0 6" fill="#f39c12"/>
            </marker>
            <marker id="arrow-water" markerWidth="6" markerHeight="6" refX="4" refY="3" orient="auto">
              <polygon points="0 0, 6 3, 0 6" fill="#3498db"/>
            </marker>
          </defs>
          
          <path d="M 45 42 Q 85 55 105 85" fill="none" stroke="#f39c12" stroke-width="2.5" class="flow-arrow" marker-end="url(#arrow-sun)"/>
          
          <path d="M 42 140 Q 75 142 98 152" fill="none" stroke="#3498db" stroke-width="2.5" class="flow-arrow" marker-end="url(#arrow-water)"/>
        </svg>

        <div class="sun-source">
          <span>☀️</span>
          <span class="source-label">Sunlight</span>
        </div>

        <div class="plant-center">🌻</div>
        <div class="soil-ground"></div>

        <div class="water-source">
          <span>💧</span>
          <span class="water-label">Water</span>
        </div>
      </div>
      <div class="bottom-badge badge-plant">Makes Own Food</div>
    </div>

    
    <div class="side-card" id="cardAnimals">
      <div class="side-title animals">Animals: Food Eaters</div>
      <div class="animal-scene">
        
        <div class="eat-row">
          <span class="actor">🐇</span>
          <span class="action-arrow">➔ eats ➔</span>
          <span class="actor">🌿</span>
        </div>
        
        <div class="eat-row">
          <span class="actor">🦅</span>
          <span class="action-arrow">➔ eats ➔</span>
          <span class="actor">🐟</span>
        </div>
      </div>
      <div class="bottom-badge badge-animal">Must Eat to Survive</div>
    </div>

  </div>

  <script>
    function setView(mode) {
      document.querySelectorAll('.tab-btn').forEach(btn => btn.classList.remove('active'));
      
      const plantsCard = document.getElementById('cardPlants');
      const animalsCard = document.getElementById('cardAnimals');

      if (mode === 'plants') {
        document.getElementById('tabPlants').classList.add('active');
        plantsCard.classList.remove('dimmed');
        animalsCard.classList.add('dimmed');
      } else if (mode === 'animals') {
        document.getElementById('tabAnimals').classList.add('active');
        plantsCard.classList.add('dimmed');
        animalsCard.classList.remove('dimmed');
      } else {
        document.getElementById('tabBoth').classList.add('active');
        plantsCard.classList.remove('dimmed');
        animalsCard.classList.remove('dimmed');
      }
    }
  </script>
</body>
</html>

Why Animals Need Nutrition: Energy, Growth, and Repair

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="1:1">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      -webkit-tap-highlight-color: transparent;
    }

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      background: transparent;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100%;
      user-select: none;
    }

    .title {
      font-size: 16px;
      font-weight: 700;
      margin-bottom: 12px;
      text-align: center;
      color: #1e2945;
    }

    .cards-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 8px;
      width: 100%;
      max-width: 440px;
      margin-bottom: 12px;
    }

    .purpose-card {
      background: #ffffff;
      border-radius: 12px;
      padding: 12px 6px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      text-align: center;
      position: relative;
      border: 2px solid transparent;
      box-shadow: 0 2px 6px rgba(0, 0, 0, 0.05);
      transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease, background-color 0.25s ease;
    }

    .purpose-card:active {
      transform: scale(0.96);
    }

    .icon-wrap {
      font-size: 32px;
      line-height: 1;
      margin-bottom: 6px;
      display: inline-block;
      transition: transform 0.3s ease;
    }

    .card-label {
      font-size: 14px;
      font-weight: 700;
      letter-spacing: -0.2px;
    }

    /* Card Themes */
    .card-energy {
      background: #fffdf0;
      border-color: #fde68a;
    }
    .card-energy.active {
      background: #fef3c7;
      border-color: #f59e0b;
      box-shadow: 0 4px 12px rgba(245, 158, 11, 0.25);
      transform: translateY(-2px);
    }
    .card-energy.active .icon-wrap {
      transform: scale(1.15);
    }

    .card-growth {
      background: #f0fdf4;
      border-color: #bbf7d0;
    }
    .card-growth.active {
      background: #dcfce7;
      border-color: #10b981;
      box-shadow: 0 4px 12px rgba(16, 185, 129, 0.25);
      transform: translateY(-2px);
    }
    .card-growth.active .icon-wrap {
      transform: scale(1.15);
    }

    .card-repair {
      background: #fff1f2;
      border-color: #fecdd3;
    }
    .card-repair.active {
      background: #ffe4e6;
      border-color: #f43f5e;
      box-shadow: 0 4px 12px rgba(244, 63, 94, 0.25);
      transform: translateY(-2px);
    }
    .card-repair.active .icon-wrap {
      transform: scale(1.15);
    }

    /* Visual Showcase Stage */
    .showcase-panel {
      width: 100%;
      max-width: 440px;
      background: #f8fafc;
      border: 1.5px solid #e2e8f0;
      border-radius: 14px;
      padding: 14px 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      min-height: 120px;
      position: relative;
      overflow: hidden;
      justify-content: center;
    }

    .stage-view {
      position: absolute;
      inset: 0;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      padding: 10px;
      opacity: 0;
      pointer-events: none;
      transform: translateY(6px);
      transition: opacity 0.3s ease, transform 0.3s ease;
    }

    .stage-view.active {
      opacity: 1;
      pointer-events: auto;
      transform: translateY(0);
    }

    .visual-row {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 12px;
      font-size: 26px;
      margin-bottom: 8px;
    }

    .arrow {
      font-size: 18px;
      color: #64748b;
      font-weight: 800;
    }

    .caption {
      font-size: 14px;
      font-weight: 600;
      color: #1e2945;
      text-align: center;
      line-height: 1.3;
    }

    /* Pulse animation on click */
    @keyframes pulseCard {
      0% { transform: scale(1); }
      50% { transform: scale(1.04); }
      100% { transform: translateY(-2px); }
    }
    .pulse-anim {
      animation: pulseCard 0.35s ease-out forwards;
    }

    /* Small size transitions */
    .grow-anim {
      display: inline-block;
      transition: transform 0.4s ease;
    }
    .stage-view.active .grow-anim {
      transform: scale(1.25);
    }
  </style>
</head>
<body>

  <div class="title">3 Reasons Animals Need Food</div>

  <div class="cards-grid" role="tablist" aria-label="Purposes of Nutrition">
    <div class="purpose-card card-energy active" id="card-0" onclick="selectStep(0)" role="tab" aria-selected="true" tabindex="0">
      <span class="icon-wrap">⚡</span>
      <span class="card-label">Energy</span>
    </div>

    <div class="purpose-card card-growth" id="card-1" onclick="selectStep(1)" role="tab" aria-selected="false" tabindex="0">
      <span class="icon-wrap">🌱</span>
      <span class="card-label">Growth</span>
    </div>

    <div class="purpose-card card-repair" id="card-2" onclick="selectStep(2)" role="tab" aria-selected="false" tabindex="0">
      <span class="icon-wrap">🩹</span>
      <span class="card-label">Repair</span>
    </div>
  </div>

  <div class="showcase-panel">
    
    <div class="stage-view active" id="view-0">
      <div class="visual-row">
        <span>🏃</span>
        <span>🫀</span>
        <span>⚡</span>
      </div>
      <div class="caption">Powers running, breathing & heartbeat</div>
    </div>

    
    <div class="stage-view" id="view-1">
      <div class="visual-row">
        <span style="font-size: 20px;">🐶</span>
        <span class="arrow">➔</span>
        <span class="grow-anim" style="font-size: 32px;">🐕</span>
      </div>
      <div class="caption">Turns a puppy into a dog</div>
    </div>

    
    <div class="stage-view" id="view-2">
      <div class="visual-row">
        <span>🩹</span>
        <span class="arrow">➔</span>
        <span style="color: #10b981; font-weight: bold; font-size: 24px;">✨ 💪</span>
      </div>
      <div class="caption">Heals scrapes & fixes muscles</div>
    </div>
  </div>

  <script>
    let activeIndex = 0;

    function selectStep(index) {
      if (activeIndex === index) return;
      activeIndex = index;

      for (let i = 0; i < 3; i++) {
        const card = document.getElementById('card-' + i);
        const view = document.getElementById('view-' + i);
        const isCurrent = (i === index);

        card.classList.toggle('active', isCurrent);
        card.setAttribute('aria-selected', isCurrent);
        view.classList.toggle('active', isCurrent);

        if (isCurrent) {
          card.classList.remove('pulse-anim');
          void card.offsetWidth; // trigger reflow for animation restart
          card.classList.add('pulse-anim');
        } else {
          card.classList.remove('pulse-anim');
        }
      }
    }

    // Keyboard support (arrow keys / Enter)
    document.querySelectorAll('.purpose-card').forEach((card, idx) => {
      card.addEventListener('keydown', (e) => {
        if (e.key === 'Enter' || e.key === ' ') {
          e.preventDefault();
          selectStep(idx);
        } else if (e.key === 'ArrowRight') {
          e.preventDefault();
          const next = (idx + 1) % 3;
          selectStep(next);
          document.getElementById('card-' + next).focus();
        } else if (e.key === 'ArrowLeft') {
          e.preventDefault();
          const prev = (idx + 2) % 3;
          selectStep(prev);
          document.getElementById('card-' + prev).focus();
        }
      });
    });
  </script>
</body>
</html>

science.ks2

Child standards (2)

Aligned learning resources

Related diagrams