<!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, sans-serif;
      background: #f8fafc;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      padding: 12px;
      user-select: none;
      -webkit-user-select: none;
    }

    .controls {
      display: flex;
      align-items: center;
      gap: 8px;
      margin-bottom: 12px;
      flex-wrap: wrap;
      justify-content: center;
    }

    .step-btn {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 20px;
      padding: 6px 14px;
      font-size: 13px;
      font-weight: 600;
      color: #64748b;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 4px;
      transition: all 0.25s ease;
    }

    .step-btn.active {
      background: #2563eb;
      color: #ffffff;
      border-color: #2563eb;
      box-shadow: 0 2px 8px rgba(37, 99, 235, 0.25);
    }

    .play-btn {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 50%;
      width: 32px;
      height: 32px;
      display: flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      font-size: 14px;
      color: #1e2945;
      transition: background 0.2s ease;
    }

    .tree-container {
      width: 100%;
      max-width: 580px;
      display: flex;
      flex-direction: column;
      gap: 10px;
    }

    /* Pool of 4 organisms */
    .pool {
      display: flex;
      justify-content: center;
      gap: 8px;
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 8px 12px;
      box-shadow: 0 1px 3px rgba(0,0,0,0.04);
    }

    .item {
      display: inline-flex;
      align-items: center;
      gap: 5px;
      padding: 4px 10px;
      border-radius: 8px;
      font-size: 13px;
      font-weight: 600;
      background: #f1f5f9;
      border: 1px solid #e2e8f0;
      transition: all 0.3s ease;
    }

    .item.highlight {
      background: #dbeafe;
      border-color: #93c5fd;
      color: #1d4ed8;
      box-shadow: 0 0 0 2px rgba(37, 99, 235, 0.2);
    }

    /* Branch row */
    .branch-card {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 10px;
      transition: all 0.35s ease;
      opacity: 0.35;
      filter: grayscale(0.6);
    }

    .branch-card.active-branch {
      opacity: 1;
      filter: none;
      border-color: #93c5fd;
      box-shadow: 0 3px 10px rgba(37, 99, 235, 0.08);
    }

    .branch-split {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 8px;
    }

    .node {
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 8px 10px;
      display: flex;
      flex-direction: column;
      gap: 6px;
    }

    .node-header {
      font-size: 13px;
      font-weight: 700;
      display: flex;
      align-items: center;
      gap: 5px;
      color: #334155;
    }

    .plant-node .node-header { color: #15803d; }
    .animal-node .node-header { color: #b45309; }
    .gills-node .node-header { color: #0284c7; }
    .lungs-node .node-header { color: #7c3aed; }
    .feather-node .node-header { color: #c026d3; }
    .fur-node .node-header { color: #ea580c; }

    .node-target {
      min-height: 32px;
      display: flex;
      flex-wrap: wrap;
      gap: 6px;
      align-items: center;
    }

    .badge-result {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      padding: 3px 8px;
      border-radius: 6px;
      font-size: 12px;
      font-weight: 600;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      box-shadow: 0 1px 2px rgba(0,0,0,0.05);
    }

    .badge-result.final {
      background: #ecfdf5;
      border-color: #a7f3d0;
      color: #065f46;
    }
  </style>
</head>
<body>

  <div class="controls">
    <button class="step-btn active" id="btn0" onclick="setStep(0)">All 🌿🐾</button>
    <button class="step-btn" id="btn1" onclick="setStep(1)">Step 1: Food</button>
    <button class="step-btn" id="btn2" onclick="setStep(2)">Step 2: Breathe</button>
    <button class="step-btn" id="btn3" onclick="setStep(3)">Step 3: Covering</button>
    <button class="play-btn" id="playBtn" onclick="togglePlay()" title="Play / Pause">▶</button>
  </div>

  <div class="tree-container">
    
    <div class="pool">
      <div class="item" id="org-sunflower">🌻 Sunflower</div>
      <div class="item" id="org-goldfish">🐟 Goldfish</div>
      <div class="item" id="org-robin">🐦 Robin</div>
      <div class="item" id="org-bear">🐻 Bear</div>
    </div>

    
    <div class="branch-card" id="card1">
      <div class="branch-split">
        <div class="node plant-node">
          <div class="node-header">🌱 Makes Food</div>
          <div class="node-target">
            <span class="badge-result final">🌻 Sunflower ✓</span>
          </div>
        </div>
        <div class="node animal-node">
          <div class="node-header">🥩 Eats Food</div>
          <div class="node-target">
            <span class="badge-result">🐟 🐦 🐻 Animals</span>
          </div>
        </div>
      </div>
    </div>

    
    <div class="branch-card" id="card2">
      <div class="branch-split">
        <div class="node gills-node">
          <div class="node-header">💧 Gills</div>
          <div class="node-target">
            <span class="badge-result final">🐟 Goldfish ✓</span>
          </div>
        </div>
        <div class="node lungs-node">
          <div class="node-header">🫁 Lungs</div>
          <div class="node-target">
            <span class="badge-result">🐦 🐻 Lungs</span>
          </div>
        </div>
      </div>
    </div>

    
    <div class="branch-card" id="card3">
      <div class="branch-split">
        <div class="node feather-node">
          <div class="node-header">🪶 Feathers</div>
          <div class="node-target">
            <span class="badge-result final">🐦 Robin ✓</span>
          </div>
        </div>
        <div class="node fur-node">
          <div class="node-header">🐾 Fur</div>
          <div class="node-target">
            <span class="badge-result final">🐻 Bear ✓</span>
          </div>
        </div>
      </div>
    </div>
  </div>

  <script>
    let currentStep = 0;
    let timer = null;
    let playing = false;

    function setStep(step) {
      currentStep = step;
      
      // Update buttons
      for (let i = 0; i <= 3; i++) {
        const btn = document.getElementById('btn' + i);
        if (btn) btn.classList.toggle('active', i === step);
      }

      const c1 = document.getElementById('card1');
      const c2 = document.getElementById('card2');
      const c3 = document.getElementById('card3');

      // Card active states
      if (step === 0) {
        c1.classList.add('active-branch');
        c2.classList.add('active-branch');
        c3.classList.add('active-branch');
      } else {
        c1.classList.toggle('active-branch', step >= 1);
        c2.classList.toggle('active-branch', step >= 2);
        c3.classList.toggle('active-branch', step >= 3);
      }

      // Highlight source organisms based on focus
      const sun = document.getElementById('org-sunflower');
      const fish = document.getElementById('org-goldfish');
      const rob = document.getElementById('org-robin');
      const bear = document.getElementById('org-bear');

      [sun, fish, rob, bear].forEach(el => el.classList.remove('highlight'));

      if (step === 1) {
        sun.classList.add('highlight');
      } else if (step === 2) {
        fish.classList.add('highlight');
      } else if (step === 3) {
        rob.classList.add('highlight');
        bear.classList.add('highlight');
      }
    }

    function togglePlay() {
      playing = !playing;
      const playBtn = document.getElementById('playBtn');
      playBtn.textContent = playing ? '⏸' : '▶';

      if (playing) {
        if (currentStep === 3) setStep(0);
        timer = setInterval(() => {
          let next = (currentStep + 1) % 4;
          setStep(next);
        }, 3000);
      } else {
        clearInterval(timer);
      }
    }

    // Initialize in resting view (all branches active)
    setStep(0);
  </script>
</body>
</html>

Why Scientists Classify Living Things

<!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;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    }

    body {
      background: transparent;
      color: #1e2945;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 12px;
    }

    /* Core takeaway banner */
    .takeaway-badge {
      background: #fee2e2;
      border: 1px solid #f87171;
      color: #b91c1c;
      font-weight: 700;
      font-size: 13px;
      padding: 6px 14px;
      border-radius: 20px;
      text-align: center;
      box-shadow: 0 1px 3px rgba(185, 28, 28, 0.1);
      display: flex;
      align-items: center;
      gap: 6px;
    }

    /* Interactive filter buttons */
    .filter-bar {
      display: flex;
      flex-wrap: wrap;
      justify-content: center;
      gap: 6px;
    }

    .filter-btn {
      background: #f1f5f9;
      border: 1px solid #cbd5e1;
      color: #475569;
      font-size: 12px;
      font-weight: 600;
      padding: 5px 10px;
      border-radius: 14px;
      cursor: pointer;
      transition: all 0.2s ease;
    }

    .filter-btn:hover {
      background: #e2e8f0;
      color: #1e2945;
    }

    .filter-btn.active {
      background: #1e2945;
      border-color: #1e2945;
      color: #ffffff;
    }

    /* Cards Layout */
    .cards-container {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 12px;
      width: 100%;
      max-width: 600px;
    }

    .animal-card {
      background: #ffffff;
      border-radius: 14px;
      padding: 12px;
      display: flex;
      flex-direction: column;
      gap: 10px;
      box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
      border: 2px solid transparent;
      transition: border-color 0.2s ease;
    }

    .card-dolphin {
      border-color: #bae6fd;
    }

    .card-shark {
      border-color: #99f6e4;
    }

    .card-header {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 4px;
    }

    .animal-icon {
      font-size: 32px;
      line-height: 1;
    }

    .animal-title {
      font-size: 16px;
      font-weight: 700;
      color: #0f172a;
    }

    /* Neutral Habitat Pill */
    .habitat-pill {
      background: #f1f5f9;
      border: 1px solid #e2e8f0;
      color: #64748b;
      font-size: 11px;
      font-weight: 600;
      padding: 3px 10px;
      border-radius: 12px;
      display: inline-flex;
      align-items: center;
      gap: 4px;
    }

    /* Trait list */
    .trait-list {
      display: flex;
      flex-direction: column;
      gap: 6px;
    }

    .trait-row {
      background: #f8fafc;
      border-radius: 8px;
      padding: 6px 8px;
      display: flex;
      flex-direction: column;
      gap: 2px;
      border: 1px solid #e2e8f0;
      transition: all 0.2s ease;
    }

    .trait-row.highlighted {
      background: #fffbeb;
      border-color: #f59e0b;
      box-shadow: 0 0 0 1px #f59e0b;
    }

    .trait-row.dimmed {
      opacity: 0.45;
    }

    .trait-label {
      font-size: 10px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.5px;
      color: #64748b;
    }

    .trait-val {
      font-size: 12.5px;
      font-weight: 600;
      color: #1e293b;
      display: flex;
      align-items: center;
      gap: 4px;
    }

    /* Group Category Highlight */
    .group-box {
      border-radius: 10px;
      padding: 8px;
      text-align: center;
      margin-top: 2px;
    }

    .group-dolphin {
      background: #e0f2fe;
      border: 1.5px solid #38bdf8;
      color: #0369a1;
    }

    .group-shark {
      background: #ccfbf1;
      border: 1.5px solid #2dd4bf;
      color: #0f766e;
    }

    .group-title {
      font-size: 10px;
      font-weight: 700;
      text-transform: uppercase;
      opacity: 0.85;
    }

    .group-name {
      font-size: 15px;
      font-weight: 800;
    }

    @media (max-width: 380px) {
      .cards-container {
        gap: 8px;
      }
      .animal-card {
        padding: 8px;
      }
      .trait-val {
        font-size: 11.5px;
      }
      .animal-title {
        font-size: 14px;
      }
    }
  </style>
</head>
<body>

  
  <div class="takeaway-badge">
    <span>⚠️</span>
    <span>Grouped by body traits, NOT where they live!</span>
  </div>

  
  <div class="filter-bar">
    <button class="filter-btn active" data-trait="all">Compare All</button>
    <button class="filter-btn" data-trait="breathes">Breathes</button>
    <button class="filter-btn" data-trait="skin">Skin</button>
    <button class="filter-btn" data-trait="babies">Babies</button>
  </div>

  
  <div class="cards-container">
    
    
    <div class="animal-card card-dolphin">
      <div class="card-header">
        <div class="animal-icon">🐬</div>
        <div class="animal-title">Dolphin</div>
        <div class="habitat-pill">🌊 Habitat: Ocean</div>
      </div>

      <div class="trait-list">
        <div class="trait-row" data-type="breathes">
          <span class="trait-label">Breathes</span>
          <span class="trait-val">🫁 Lungs (air)</span>
        </div>
        <div class="trait-row" data-type="skin">
          <span class="trait-label">Skin</span>
          <span class="trait-val">✨ Smooth skin</span>
        </div>
        <div class="trait-row" data-type="babies">
          <span class="trait-label">Babies</span>
          <span class="trait-val">🥛 Drinks milk</span>
        </div>
      </div>

      <div class="group-box group-dolphin">
        <div class="group-title">Classification</div>
        <div class="group-name">Mammal</div>
      </div>
    </div>

    
    <div class="animal-card card-shark">
      <div class="card-header">
        <div class="animal-icon">🦈</div>
        <div class="animal-title">Shark</div>
        <div class="habitat-pill">🌊 Habitat: Ocean</div>
      </div>

      <div class="trait-list">
        <div class="trait-row" data-type="breathes">
          <span class="trait-label">Breathes</span>
          <span class="trait-val">🫧 Gills (water)</span>
        </div>
        <div class="trait-row" data-type="skin">
          <span class="trait-label">Skin</span>
          <span class="trait-val">🛡️ Rough denticles</span>
        </div>
        <div class="trait-row" data-type="babies">
          <span class="trait-label">Babies</span>
          <span class="trait-val">🥚 Eggs / No milk</span>
        </div>
      </div>

      <div class="group-box group-shark">
        <div class="group-title">Classification</div>
        <div class="group-name">Fish</div>
      </div>
    </div>

  </div>

  <script>
    const buttons = document.querySelectorAll('.filter-btn');
    const traitRows = document.querySelectorAll('.trait-row');

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

        const selected = btn.getAttribute('data-trait');

        traitRows.forEach(row => {
          const type = row.getAttribute('data-type');
          if (selected === 'all') {
            row.classList.remove('highlighted', 'dimmed');
          } else if (type === selected) {
            row.classList.add('highlighted');
            row.classList.remove('dimmed');
          } else {
            row.classList.remove('highlighted');
            row.classList.add('dimmed');
          }
        });
      });
    });
  </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;
      -webkit-tap-highlight-color: transparent;
    }

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e293b;
      background: transparent;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      padding: 8px;
    }

    .board {
      width: 100%;
      max-width: 620px;
      display: grid;
      grid-template-columns: 1fr auto 1.25fr;
      gap: 10px;
      align-items: stretch;
    }

    @media (max-width: 500px) {
      .board {
        grid-template-columns: 1fr;
        gap: 8px;
      }
      .arrow-col {
        transform: rotate(90deg);
        margin: 2px 0;
      }
    }

    .section-title {
      font-size: 12px;
      font-weight: 800;
      text-transform: uppercase;
      letter-spacing: 0.6px;
      margin-bottom: 8px;
      text-align: center;
    }

    .unsorted-box {
      background: #f8fafc;
      border: 2px dashed #cbd5e1;
      border-radius: 12px;
      padding: 10px;
      display: flex;
      flex-direction: column;
      justify-content: flex-start;
    }

    .unsorted-title {
      color: #64748b;
    }

    .jumble-grid {
      display: flex;
      flex-wrap: wrap;
      gap: 6px;
      justify-content: center;
      align-content: center;
      flex: 1;
      padding: 4px 0;
    }

    .item-chip {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      padding: 5px 8px;
      font-size: 12px;
      font-weight: 600;
      display: inline-flex;
      align-items: center;
      gap: 5px;
      box-shadow: 0 1px 3px rgba(0,0,0,0.05);
      user-select: none;
      transition: box-shadow 0.2s ease, border-color 0.2s ease;
    }

    .jumble-grid .item-chip:nth-child(1) { transform: rotate(-3deg); }
    .jumble-grid .item-chip:nth-child(2) { transform: rotate(4deg); }
    .jumble-grid .item-chip:nth-child(3) { transform: rotate(-2deg); }
    .jumble-grid .item-chip:nth-child(4) { transform: rotate(3deg); }
    .jumble-grid .item-chip:nth-child(5) { transform: rotate(-4deg); }
    .jumble-grid .item-chip:nth-child(6) { transform: rotate(2deg); }

    .arrow-col {
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 4px;
    }

    .sort-btn {
      background: #0284c7;
      color: white;
      border: none;
      border-radius: 50%;
      width: 38px;
      height: 38px;
      font-size: 16px;
      display: flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      box-shadow: 0 3px 8px rgba(2, 132, 199, 0.3);
      transition: background 0.2s ease, box-shadow 0.2s ease;
    }

    .sort-btn:hover {
      background: #0369a1;
      box-shadow: 0 4px 10px rgba(2, 132, 199, 0.45);
    }

    .sort-btn:active {
      background: #075985;
    }

    .sort-label {
      font-size: 10px;
      font-weight: 700;
      color: #0284c7;
      text-transform: uppercase;
      letter-spacing: 0.5px;
    }

    .sorted-box {
      display: flex;
      flex-direction: column;
      gap: 6px;
    }

    .sorted-title {
      color: #0284c7;
    }

    .bin {
      border-radius: 10px;
      padding: 6px 9px;
      border: 1.5px solid transparent;
      transition: box-shadow 0.25s ease, border-color 0.25s ease, background-color 0.25s ease;
      cursor: pointer;
    }

    .bin-fur {
      background: #fff7ed;
      border-color: #ffedd5;
    }

    .bin-feathers {
      background: #f0fdf4;
      border-color: #dcfce7;
    }

    .bin-aquatic {
      background: #f0f9ff;
      border-color: #e0f2fe;
    }

    .bin-plants {
      background: #fdf2f8;
      border-color: #fce7f3;
    }

    .bin-header {
      font-size: 11px;
      font-weight: 700;
      margin-bottom: 4px;
      display: flex;
      align-items: center;
      gap: 5px;
    }

    .bin-fur .bin-header { color: #c2410c; }
    .bin-feathers .bin-header { color: #15803d; }
    .bin-aquatic .bin-header { color: #0369a1; }
    .bin-plants .bin-header { color: #be185d; }

    .bin-items {
      display: flex;
      flex-wrap: wrap;
      gap: 5px;
    }

    .bin .item-chip {
      padding: 3px 7px;
      font-size: 11.5px;
      box-shadow: 0 1px 2px rgba(0,0,0,0.03);
    }

    .bin.active-bin {
      box-shadow: 0 0 0 2px #0284c7, 0 3px 8px rgba(2, 132, 199, 0.18);
      border-color: #38bdf8;
    }
  </style>
</head>
<body>

  <div class="board">
    
    <div class="unsorted-box">
      <div class="section-title unsorted-title">Messy Nature (Unsorted)</div>
      <div class="jumble-grid" id="unsortedGrid">
        <div class="item-chip"><span>🐕</span> Dog</div>
        <div class="item-chip"><span>🌹</span> Rose</div>
        <div class="item-chip"><span>🦅</span> Eagle</div>
        <div class="item-chip"><span>🐸</span> Frog</div>
        <div class="item-chip"><span>🌿</span> Fern</div>
        <div class="item-chip"><span>🐠</span> Clownfish</div>
      </div>
    </div>

    
    <div class="arrow-col">
      <button class="sort-btn" id="sortTrigger" title="Click to cycle groups" aria-label="Sort into groups">➔</button>
      <span class="sort-label">Sort</span>
    </div>

    
    <div class="sorted-box">
      <div class="section-title sorted-title">Classified Groups (Sorted)</div>

      
      <div class="bin bin-fur" id="binFur">
        <div class="bin-header"><span>🐾</span> Animals with Fur</div>
        <div class="bin-items">
          <div class="item-chip"><span>🐕</span> Dog</div>
        </div>
      </div>

      
      <div class="bin bin-feathers" id="binFeathers">
        <div class="bin-header"><span>🪶</span> Animals with Feathers</div>
        <div class="bin-items">
          <div class="item-chip"><span>🦅</span> Eagle</div>
        </div>
      </div>

      
      <div class="bin bin-aquatic" id="binAquatic">
        <div class="bin-header"><span>🌊</span> Fish & Amphibians</div>
        <div class="bin-items">
          <div class="item-chip"><span>🐸</span> Frog</div>
          <div class="item-chip"><span>🐠</span> Clownfish</div>
        </div>
      </div>

      
      <div class="bin bin-plants" id="binPlants">
        <div class="bin-header"><span>🌱</span> Plants</div>
        <div class="bin-items">
          <div class="item-chip"><span>🌿</span> Fern</div>
          <div class="item-chip"><span>🌹</span> Rose</div>
        </div>
      </div>
    </div>
  </div>

  <script>
    const sortBtn = document.getElementById('sortTrigger');
    const bins = [
      document.getElementById('binFur'),
      document.getElementById('binFeathers'),
      document.getElementById('binAquatic'),
      document.getElementById('binPlants')
    ];
    let step = 0;

    function highlightNextBin() {
      bins.forEach(b => b.classList.remove('active-bin'));
      const activeBin = bins[step % bins.length];
      activeBin.classList.add('active-bin');
      step++;
    }

    sortBtn.addEventListener('click', () => {
      highlightNextBin();
    });

    bins.forEach((bin, idx) => {
      bin.addEventListener('click', () => {
        bins.forEach(b => b.classList.remove('active-bin'));
        bin.classList.add('active-bin');
        step = idx + 1;
      });
    });

    let autoInterval = setInterval(highlightNextBin, 2500);

    const stopAuto = () => clearInterval(autoInterval);
    sortBtn.addEventListener('mouseenter', stopAuto);
    sortBtn.addEventListener('touchstart', stopAuto, { passive: true });
    bins.forEach(bin => {
      bin.addEventListener('mouseenter', stopAuto);
      bin.addEventListener('touchstart', stopAuto, { passive: true });
    });
  </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 {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      background: transparent;
      padding: 8px;
      display: flex;
      flex-direction: column;
      user-select: none;
      -webkit-user-select: none;
    }

    .container {
      display: flex;
      flex-direction: row;
      gap: 12px;
      width: 100%;
      max-width: 720px;
      margin: 0 auto;
    }

    .column {
      background: #f8fafc;
      border-radius: 12px;
      border: 1px solid #e2e8f0;
      padding: 12px;
      flex: 1;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      gap: 8px;
      text-align: center;
      min-width: 0;
    }

    .pill {
      font-size: 11px;
      font-weight: 700;
      padding: 5px 10px;
      border-radius: 20px;
      letter-spacing: 0.2px;
      display: inline-block;
      line-height: 1.3;
      text-align: center;
    }

    .pill-vert {
      background: #e0f2fe;
      color: #075985;
      border: 1px solid #bae6fd;
    }

    .pill-invert {
      background: #ffe4e6;
      color: #9f1239;
      border: 1px solid #fecdd3;
    }

    .visual-box {
      width: 100%;
      display: flex;
      align-items: center;
      justify-content: center;
      padding: 4px 0;
    }

    svg {
      width: 100%;
      max-width: 240px;
      height: auto;
      max-height: 135px;
      overflow: visible;
      display: block;
    }

    .caption {
      font-size: 12.5px;
      font-weight: 700;
      padding: 5px 12px;
      border-radius: 6px;
      display: inline-block;
    }

    .caption-vert {
      color: #0369a1;
      background: #e0f2fe;
      border: 1px solid #bae6fd;
    }

    .caption-invert {
      color: #be123c;
      background: #ffe4e6;
      border: 1px solid #fecdd3;
    }

    .sub-labels {
      display: flex;
      justify-content: space-around;
      width: 100%;
      font-size: 10.5px;
      font-weight: 600;
      color: #64748b;
      margin-top: -4px;
    }

    .backbone-pulse {
      animation: gentleGlow 3s ease-in-out infinite;
    }

    @keyframes gentleGlow {
      0%, 100% {
        stroke-opacity: 0.85;
        stroke-width: 3.5px;
      }
      50% {
        stroke-opacity: 1;
        stroke-width: 4.5px;
      }
    }

    /* Responsive mobile layout */
    @media (max-width: 500px) {
      .container {
        flex-direction: column;
        gap: 10px;
      }

      .column {
        padding: 10px 8px;
        gap: 6px;
      }

      svg {
        max-height: 110px;
      }

      .pill {
        font-size: 10.5px;
        padding: 4px 8px;
      }

      .caption {
        font-size: 11.5px;
        padding: 4px 10px;
      }
    }
  </style>
</head>
<body>

  <div class="container">
    
    <div class="column">
      <div class="pill pill-vert">Vertebrates (5% of all animal species)</div>
      
      <div class="visual-box">
        <svg viewBox="0 0 200 120" role="img" aria-label="Fish skeleton showing internal backbone">
          
          <path d="M 25,60 C 45,25 115,20 165,50 L 185,33 L 185,87 L 165,70 C 115,100 45,95 25,60 Z" 
                fill="#f0f9ff" stroke="#cbd5e1" stroke-width="1.5" stroke-dasharray="3,3" />
          
          
          <path d="M 30,60 C 33,47 50,43 55,55 C 55,67 33,73 30,60 Z" fill="#94a3b8" />
          <circle cx="42" cy="53" r="2.5" fill="#f8fafc" />

          
          <line x1="165" y1="60" x2="182" y2="39" stroke="#94a3b8" stroke-width="1.5" />
          <line x1="165" y1="60" x2="184" y2="53" stroke="#94a3b8" stroke-width="1.5" />
          <line x1="165" y1="60" x2="184" y2="67" stroke="#94a3b8" stroke-width="1.5" />
          <line x1="165" y1="60" x2="182" y2="81" stroke="#94a3b8" stroke-width="1.5" />

          
          <g stroke="#94a3b8" stroke-width="1.5" stroke-linecap="round">
            <line x1="68" y1="60" x2="74" y2="43" />
            <line x1="82" y1="60" x2="90" y2="41" />
            <line x1="96" y1="60" x2="106" y2="42" />
            <line x1="110" y1="60" x2="122" y2="45" />
            <line x1="124" y1="60" x2="136" y2="48" />
            <line x1="138" y1="60" x2="148" y2="52" />

            <line x1="68" y1="60" x2="74" y2="77" />
            <line x1="82" y1="60" x2="90" y2="79" />
            <line x1="96" y1="60" x2="106" y2="78" />
            <line x1="110" y1="60" x2="122" y2="75" />
            <line x1="124" y1="60" x2="136" y2="72" />
            <line x1="138" y1="60" x2="148" y2="68" />
          </g>

          
          <line class="backbone-pulse" x1="53" y1="60" x2="165" y2="60" stroke="#0284c7" stroke-linecap="round" />

          
          <g fill="#0369a1">
            <circle cx="55" cy="60" r="3" />
            <circle cx="69" cy="60" r="3" />
            <circle cx="83" cy="60" r="3" />
            <circle cx="97" cy="60" r="3" />
            <circle cx="111" cy="60" r="3" />
            <circle cx="125" cy="60" r="3" />
            <circle cx="139" cy="60" r="3" />
            <circle cx="153" cy="60" r="3" />
            <circle cx="165" cy="60" r="3" />
          </g>
        </svg>
      </div>

      <div class="caption caption-vert">Internal Backbone</div>
    </div>

    
    <div class="column">
      <div class="pill pill-invert">Invertebrates (95% of all animal species)</div>
      
      <div class="visual-box">
        <svg viewBox="0 0 200 120" role="img" aria-label="Ant with exoskeleton and soft-bodied jellyfish">
          
          <g transform="translate(14, 18)">
            
            <g stroke="#94a3b8" stroke-width="1.5" stroke-linecap="round" fill="none">
              
              <path d="M 28,26 Q 16,16 10,22" />
              <path d="M 33,28 Q 24,38 18,48" />
              <path d="M 37,30 Q 30,46 26,56" />
              
              <path d="M 32,22 Q 44,12 50,16" />
              <path d="M 36,25 Q 52,28 58,38" />
              <path d="M 40,28 Q 56,42 62,52" />
              
              <path d="M 23,12 Q 18,4 12,5" />
              <path d="M 26,10 Q 28,2 34,2" />
            </g>
            
            
            <ellipse cx="25" cy="14" rx="6" ry="5" fill="#ffe4e6" stroke="#e11d48" stroke-width="1.8" />
            
            <ellipse cx="34" cy="25" rx="5" ry="7" transform="rotate(-20 34 25)" fill="#ffe4e6" stroke="#e11d48" stroke-width="1.8" />
            
            <ellipse cx="48" cy="38" rx="9" ry="13" transform="rotate(-35 48 38)" fill="#ffe4e6" stroke="#e11d48" stroke-width="1.8" />
          </g>

          
          <g transform="translate(112, 16)">
            
            <path d="M 10,44 C 10,10 60,10 60,44 C 48,41 42,46 35,42 C 28,46 22,41 10,44 Z" 
                  fill="#ffe4e6" fill-opacity="0.8" stroke="#e11d48" stroke-width="1.8" />
            
            <path d="M 20,36 C 22,23 48,23 50,36" fill="none" stroke="#f43f5e" stroke-width="1.2" stroke-dasharray="2,2" />
            
            <g stroke="#e11d48" stroke-width="1.5" fill="none" stroke-linecap="round">
              <path d="M 18,44 Q 12,58 20,70 Q 26,80 18,90" />
              <path d="M 27,43 Q 32,58 26,70 Q 20,82 28,91" />
              <path d="M 36,43 Q 44,56 36,70 Q 30,82 40,92" />
              <path d="M 45,43 Q 38,58 46,70 Q 54,80 47,90" />
              <path d="M 53,44 Q 60,58 52,70 Q 46,80 54,89" />
            </g>
          </g>
        </svg>
      </div>

      <div class="sub-labels">
        <span>Ant (Exoskeleton)</span>
        <span>Jellyfish (Soft body)</span>
      </div>

      <div class="caption caption-invert">No Backbone Inside</div>
    </div>
  </div>

</body>
</html>

Vertebrates vs Invertebrates

<!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">
  <title>Vertebrates vs Invertebrates</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      user-select: none;
      -webkit-user-select: none;
    }

    body {
      background: #f8fafc;
      color: #1e2945;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-start;
      min-height: 100%;
    }

    .tree {
      width: 100%;
      max-width: 480px;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 10px;
    }

    /* Question Node */
    .question-card {
      background: #ffffff;
      border: 2px solid #0284c7;
      border-radius: 12px;
      padding: 10px 16px;
      text-align: center;
      box-shadow: 0 2px 6px rgba(2, 132, 199, 0.12);
      width: 90%;
      max-width: 320px;
    }

    .question-title {
      font-size: 15px;
      font-weight: 700;
      color: #0369a1;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 6px;
    }

    /* Branching Connectors */
    .branch-container {
      width: 100%;
      display: flex;
      flex-direction: column;
      align-items: center;
    }

    .branch-svg {
      width: 100%;
      height: 28px;
      overflow: visible;
    }

    /* Columns */
    .columns {
      width: 100%;
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 10px;
    }

    .category-col {
      display: flex;
      flex-direction: column;
      gap: 8px;
    }

    /* Category Headers */
    .cat-header {
      border-radius: 10px;
      padding: 8px 6px;
      text-align: center;
    }

    .cat-yes {
      background: #ecfdf5;
      border: 2px solid #10b981;
      color: #047857;
    }

    .cat-no {
      background: #fef3c7;
      border: 2px solid #f59e0b;
      color: #b45309;
    }

    .cat-tag {
      font-size: 11px;
      font-weight: 800;
      letter-spacing: 0.5px;
      text-transform: uppercase;
      opacity: 0.9;
    }

    .cat-name {
      font-size: 15px;
      font-weight: 800;
      margin-top: 2px;
    }

    /* Animal Cards */
    .animal-card {
      background: #ffffff;
      border: 1.5px solid #e2e8f0;
      border-radius: 10px;
      padding: 8px 10px;
      cursor: pointer;
      display: flex;
      flex-direction: column;
      gap: 4px;
      transition: border-color 0.2s, box-shadow 0.2s;
    }

    .animal-card:active {
      background: #f1f5f9;
    }

    .animal-card.revealed.vert {
      border-color: #10b981;
      box-shadow: 0 2px 8px rgba(16, 185, 129, 0.15);
    }

    .animal-card.revealed.invert {
      border-color: #f59e0b;
      box-shadow: 0 2px 8px rgba(245, 158, 11, 0.15);
    }

    .animal-main {
      display: flex;
      align-items: center;
      justify-content: space-between;
    }

    .animal-identity {
      display: flex;
      align-items: center;
      gap: 6px;
      font-size: 14px;
      font-weight: 700;
      color: #1e293b;
    }

    .animal-icon {
      font-size: 18px;
    }

    .toggle-btn {
      font-size: 10px;
      font-weight: 700;
      padding: 3px 6px;
      border-radius: 6px;
      background: #f1f5f9;
      color: #64748b;
    }

    .revealed .toggle-btn {
      background: #e2e8f0;
      color: #334155;
    }

    /* Hidden Clue Reveal */
    .clue-box {
      font-size: 12px;
      font-weight: 600;
      padding: 4px 6px;
      border-radius: 6px;
      display: none;
      align-items: center;
      gap: 4px;
      margin-top: 2px;
    }

    .vert .clue-box {
      background: #ecfdf5;
      color: #065f46;
    }

    .invert .clue-box {
      background: #fffbeb;
      color: #92400e;
    }

    .animal-card.revealed .clue-box {
      display: flex;
    }

    /* Footer prompt */
    .prompt {
      margin-top: 8px;
      font-size: 12px;
      font-weight: 600;
      color: #64748b;
      text-align: center;
    }
  </style>
</head>
<body>

  <div class="tree">
    
    <div class="question-card">
      <div class="question-title">
        <span>🦴</span> Internal backbone?
      </div>
    </div>

    
    <div class="branch-container">
      <svg class="branch-svg" viewBox="0 0 300 28" preserveAspectRatio="none">
        <path d="M 150 0 L 150 10 L 75 10 L 75 28" fill="none" stroke="#10b981" stroke-width="2.5" stroke-linecap="round" />
        <path d="M 150 0 L 150 10 L 225 10 L 225 28" fill="none" stroke="#f59e0b" stroke-width="2.5" stroke-linecap="round" />
        <circle cx="150" cy="0" r="3" fill="#0284c7" />
      </svg>
    </div>

    
    <div class="columns">
      
      
      <div class="category-col">
        <div class="cat-header cat-yes">
          <div class="cat-tag">✓ YES</div>
          <div class="cat-name">Vertebrate</div>
        </div>

        <div class="animal-card vert" onclick="toggleCard(this)">
          <div class="animal-main">
            <div class="animal-identity">
              <span class="animal-icon">🐦</span> Robin
            </div>
            <span class="toggle-btn">Inspect 🦴</span>
          </div>
          <div class="clue-box">
            <span>🦴</span> Spine inside body
          </div>
        </div>

        <div class="animal-card vert" onclick="toggleCard(this)">
          <div class="animal-main">
            <div class="animal-identity">
              <span class="animal-icon">🐍</span> Snake
            </div>
            <span class="toggle-btn">Inspect 🦴</span>
          </div>
          <div class="clue-box">
            <span>🦴</span> Long bendy spine
          </div>
        </div>
      </div>

      
      <div class="category-col">
        <div class="cat-header cat-no">
          <div class="cat-tag">✗ NO</div>
          <div class="cat-name">Invertebrate</div>
        </div>

        <div class="animal-card invert" onclick="toggleCard(this)">
          <div class="animal-main">
            <div class="animal-identity">
              <span class="animal-icon">🐌</span> Snail
            </div>
            <span class="toggle-btn">Inspect 🔍</span>
          </div>
          <div class="clue-box">
            <span>🐚</span> Soft body + shell
          </div>
        </div>

        <div class="animal-card invert" onclick="toggleCard(this)">
          <div class="animal-main">
            <div class="animal-identity">
              <span class="animal-icon">🕷️</span> Spider
            </div>
            <span class="toggle-btn">Inspect 🔍</span>
          </div>
          <div class="clue-box">
            <span>🛡️</span> Hard exoskeleton
          </div>
        </div>
      </div>

    </div>

    <div class="prompt">Tap each animal to check its structure</div>
  </div>

  <script>
    function toggleCard(card) {
      card.classList.toggle('revealed');
      const btn = card.querySelector('.toggle-btn');
      if (card.classList.contains('revealed')) {
        btn.textContent = 'Hide';
      } else {
        btn.textContent = card.classList.contains('vert') ? 'Inspect 🦴' : 'Inspect 🔍';
      }
    }
  </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="1:1">
  <title>Vertebrates: The Internal Backbone</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      width: 100%;
      min-height: 100%;
      background: #ffffff;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      padding: 12px;
      gap: 10px;
    }

    /* Top Badge */
    .badge {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      background: #eff9ff;
      border: 1.5px solid #22b7ff;
      color: #1e2945;
      font-size: 13px;
      font-weight: 700;
      padding: 6px 14px;
      border-radius: 999px;
      text-transform: uppercase;
      letter-spacing: 0.3px;
    }

    .badge-icon {
      color: #22b7ff;
      font-size: 15px;
    }

    /* Main Showcase */
    .showcase {
      width: 100%;
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 10px;
      flex: 1;
      max-height: 280px;
    }

    .animal-card {
      background: #f8fafc;
      border: 1.5px solid #e6e6e6;
      border-radius: 12px;
      padding: 8px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      position: relative;
      cursor: pointer;
      user-select: none;
      transition: border-color 0.2s ease, box-shadow 0.2s ease;
    }

    .animal-card:active, .animal-card.active {
      border-color: #22b7ff;
      box-shadow: 0 0 0 2px rgba(34, 183, 255, 0.2);
    }

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

    .svg-container {
      width: 100%;
      height: 100%;
      max-height: 180px;
      display: flex;
      align-items: center;
      justify-content: center;
    }

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

    /* Spine styles */
    .vertebra {
      fill: #22b7ff;
      stroke: #ffffff;
      stroke-width: 1.2;
      transition: transform 0.2s ease, fill 0.2s ease;
      transform-origin: center;
    }

    .spine-path {
      stroke: #22b7ff;
      stroke-width: 3.5;
      stroke-linecap: round;
      fill: none;
      filter: drop-shadow(0 0 3px rgba(34, 183, 255, 0.5));
    }

    .silhouette {
      fill: #e2e8f0;
      stroke: #cbd5e1;
      stroke-width: 1.5;
    }

    /* Backbone Callout Label */
    .spine-label {
      background: #1e2945;
      color: #ffffff;
      font-size: 11px;
      font-weight: 700;
      padding: 3px 8px;
      border-radius: 6px;
      white-space: nowrap;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      box-shadow: 0 2px 5px rgba(0, 0, 0, 0.12);
    }

    .spine-label::before {
      content: "✦";
      color: #22b7ff;
      font-size: 10px;
    }

    /* Pulse animation */
    @keyframes spinePulse {
      0%, 100% { transform: scale(1); filter: brightness(1); }
      50% { transform: scale(1.35); filter: brightness(1.2); }
    }

    .pulsing .vertebra {
      animation: spinePulse 1.2s ease-in-out infinite;
    }

    .pulsing .vertebra:nth-child(2) { animation-delay: 0.1s; }
    .pulsing .vertebra:nth-child(3) { animation-delay: 0.2s; }
    .pulsing .vertebra:nth-child(4) { animation-delay: 0.3s; }
    .pulsing .vertebra:nth-child(5) { animation-delay: 0.4s; }
    .pulsing .vertebra:nth-child(6) { animation-delay: 0.5s; }
    .pulsing .vertebra:nth-child(7) { animation-delay: 0.6s; }
    .pulsing .vertebra:nth-child(8) { animation-delay: 0.7s; }

    /* Other Vertebrates Gallery */
    .group-panel {
      width: 100%;
      background: #f8fafc;
      border: 1.5px solid #e6e6e6;
      border-radius: 12px;
      padding: 8px 12px;
      display: flex;
      justify-content: space-around;
      align-items: center;
      gap: 6px;
    }

    .group-item {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 2px;
      cursor: pointer;
      padding: 4px 6px;
      border-radius: 8px;
      border: 1.5px solid transparent;
      transition: background-color 0.15s ease, border-color 0.15s ease;
    }

    .group-item:active, .group-item.selected {
      background: #ffffff;
      border-color: #22b7ff;
    }

    .group-icon {
      font-size: 22px;
      line-height: 1;
    }

    .group-name {
      font-size: 11px;
      font-weight: 600;
      color: #1e2945;
    }

    @media (max-width: 380px) {
      .badge { font-size: 11px; padding: 4px 10px; }
      .group-icon { font-size: 18px; }
      .group-name { font-size: 10px; }
      .spine-label { font-size: 10px; }
    }
  </style>
</head>
<body>

  
  <div class="badge">
    <span class="badge-icon">🦴</span>
    VERTEBRATE = Has an internal backbone
  </div>

  
  <div class="showcase">
    
    
    <div class="animal-card active pulsing" id="humanCard" onclick="triggerPulse('humanCard')">
      <div class="animal-title">Human</div>
      <div class="svg-container">
        <svg viewBox="0 0 120 180">
          
          <path class="silhouette" d="
            M 60,18
            C 67,18 72,24 72,32
            C 72,39 67,45 61,46
            C 68,48 76,52 82,59
            C 88,67 85,90 84,105
            L 76,105
            C 76,93 78,74 74,68
            C 72,66 70,68 70,75
            L 72,118
            L 76,168
            L 65,168
            L 62,125
            L 58,125
            L 55,168
            L 44,168
            L 48,118
            L 50,75
            C 50,68 48,66 46,68
            C 42,74 44,93 44,105
            L 36,105
            C 35,90 32,67 38,59
            C 44,52 52,48 59,46
            C 53,45 48,39 48,32
            C 48,24 53,18 60,18 Z
          " />
          
          
          <path class="spine-path" d="M 60,44 C 61,56 58,68 60,82 C 61,94 59,106 60,116" />
          
          
          <g id="humanVertebrae">
            <circle class="vertebra" cx="60" cy="46" r="3.2" />
            <circle class="vertebra" cx="60.5" cy="56" r="3.2" />
            <circle class="vertebra" cx="59.5" cy="66" r="3.2" />
            <circle class="vertebra" cx="59" cy="76" r="3.2" />
            <circle class="vertebra" cx="60" cy="86" r="3.2" />
            <circle class="vertebra" cx="60.5" cy="96" r="3.2" />
            <circle class="vertebra" cx="59.5" cy="106" r="3.2" />
            <circle class="vertebra" cx="60" cy="115" r="3.2" />
          </g>
        </svg>
      </div>
      <div class="spine-label">Backbone (Vertebrae)</div>
    </div>

    
    <div class="animal-card pulsing" id="dogCard" onclick="triggerPulse('dogCard')">
      <div class="animal-title">Dog</div>
      <div class="svg-container">
        <svg viewBox="0 0 160 140">
          
          <path class="silhouette" d="
            M 134,36
            C 142,42 145,50 142,56
            C 139,60 134,60 128,58
            L 125,66
            L 128,118
            L 118,118
            L 116,78
            C 106,78 90,80 82,82
            L 80,118
            L 70,118
            L 72,86
            C 64,88 56,92 48,96
            L 44,124
            L 34,124
            L 38,88
            C 34,84 30,76 28,68
            C 20,62 14,48 20,44
            C 24,42 28,48 32,56
            C 42,50 56,48 76,49
            C 96,50 114,46 122,34
            C 126,30 130,32 134,36 Z
          " />

          
          <path class="spine-path" d="M 125,44 C 114,51 92,52 68,52 C 50,52 38,58 26,52" />

          
          <g id="dogVertebrae">
            <circle class="vertebra" cx="122" cy="46" r="3.2" />
            <circle class="vertebra" cx="110" cy="50" r="3.2" />
            <circle class="vertebra" cx="96" cy="51.5" r="3.2" />
            <circle class="vertebra" cx="82" cy="52" r="3.2" />
            <circle class="vertebra" cx="68" cy="52" r="3.2" />
            <circle class="vertebra" cx="54" cy="53" r="3.2" />
            <circle class="vertebra" cx="40" cy="55" r="3.2" />
            <circle class="vertebra" cx="28" cy="52" r="3.2" />
          </g>
        </svg>
      </div>
      <div class="spine-label">Backbone (Vertebrae)</div>
    </div>

  </div>

  
  <div class="group-panel">
    <div class="group-item" onclick="selectGroup(this)">
      <span class="group-icon">🐟</span>
      <span class="group-name">Fish</span>
    </div>
    <div class="group-item" onclick="selectGroup(this)">
      <span class="group-icon">🐦</span>
      <span class="group-name">Bird</span>
    </div>
    <div class="group-item" onclick="selectGroup(this)">
      <span class="group-icon">🐸</span>
      <span class="group-name">Frog</span>
    </div>
    <div class="group-item" onclick="selectGroup(this)">
      <span class="group-icon">🐍</span>
      <span class="group-name">Snake</span>
    </div>
    <div class="group-item" onclick="selectGroup(this)">
      <span class="group-icon">🐱</span>
      <span class="group-name">Cat</span>
    </div>
  </div>

  <script>
    function triggerPulse(cardId) {
      const card = document.getElementById(cardId);
      card.classList.remove('pulsing');
      void card.offsetWidth; // trigger reflow
      card.classList.add('pulsing');
    }

    function selectGroup(el) {
      document.querySelectorAll('.group-item').forEach(item => item.classList.remove('selected'));
      el.classList.add('selected');
      triggerPulse('humanCard');
      triggerPulse('dogCard');
    }
  </script>
</body>
</html>

The Journey of Food: Overview of the Digestive System

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Small vs Large Intestine</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #0f172a;
      background: transparent;
      padding: 8px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-start;
      min-height: auto;
    }
    .container {
      width: 100%;
      max-width: 680px;
      display: flex;
      flex-direction: column;
      gap: 10px;
    }
    .grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 12px;
      width: 100%;
    }
    .organ-panel {
      background: #f8fafc;
      border: 2px solid #e2e8f0;
      border-radius: 12px;
      padding: 12px 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      cursor: pointer;
      user-select: none;
      transition: background-color 0.25s ease, border-color 0.25s ease, box-shadow 0.25s ease;
    }
    .organ-panel.active {
      background: #ffffff;
      border-color: #3b82f6;
      box-shadow: 0 4px 12px rgba(59, 130, 246, 0.12);
    }
    .organ-panel:focus-visible {
      outline: 2px solid #0284c7;
      outline-offset: 2px;
    }
    .title {
      font-size: 15px;
      font-weight: 800;
      line-height: 1.2;
      color: #0f172a;
    }
    .pill {
      display: inline-block;
      font-size: 11px;
      font-weight: 700;
      padding: 2px 8px;
      border-radius: 10px;
      margin: 4px 0 6px 0;
      letter-spacing: 0.2px;
    }
    .pill-small {
      background: #fce7f3;
      color: #9d174d;
    }
    .pill-large {
      background: #ffedd5;
      color: #9a3412;
    }
    .svg-wrap {
      width: 100%;
      height: 155px;
      display: flex;
      align-items: center;
      justify-content: center;
    }
    svg {
      width: 100%;
      height: 100%;
      max-height: 155px;
      overflow: visible;
    }
    .tag {
      font-size: 12px;
      font-weight: 700;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 4px;
      margin-top: 6px;
      padding: 4px 10px;
      border-radius: 6px;
    }
    .tag-sparkle {
      color: #854d0e;
      background: #fef3c7;
    }
    .tag-water {
      color: #0369a1;
      background: #e0f2fe;
    }

    .info-box {
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 10px 14px;
      font-size: 12.5px;
      line-height: 1.45;
      color: #334155;
      text-align: center;
      min-height: 42px;
      display: flex;
      align-items: center;
      justify-content: center;
    }
    .info-box strong {
      color: #0f172a;
      margin-right: 4px;
    }

    /* Slow, smooth particle absorption animations (4.5s cycle, continuous and flicker-free) */
    @keyframes sparkleAbsorb {
      0% {
        opacity: 0;
        transform: translate(0, 0) scale(0.6);
      }
      20% {
        opacity: 0.95;
        transform: translate(8px, -4px) scale(1);
      }
      65% {
        opacity: 0.95;
        transform: translate(24px, -12px) scale(1.05);
      }
      90% {
        opacity: 0.15;
        transform: translate(34px, -16px) scale(0.7);
      }
      100% {
        opacity: 0;
        transform: translate(38px, -18px) scale(0.5);
      }
    }

    @keyframes waterAbsorbLeft {
      0% {
        opacity: 0;
        transform: translate(0, 0) scale(0.65);
      }
      20% {
        opacity: 0.95;
        transform: translate(-6px, 2px) scale(1);
      }
      65% {
        opacity: 0.95;
        transform: translate(-18px, 6px) scale(1.05);
      }
      90% {
        opacity: 0.15;
        transform: translate(-26px, 8px) scale(0.7);
      }
      100% {
        opacity: 0;
        transform: translate(-30px, 9px) scale(0.5);
      }
    }

    @keyframes waterAbsorbTop {
      0% {
        opacity: 0;
        transform: translate(0, 0) scale(0.65);
      }
      20% {
        opacity: 0.95;
        transform: translate(0, -4px) scale(1);
      }
      65% {
        opacity: 0.95;
        transform: translate(0, -14px) scale(1.05);
      }
      90% {
        opacity: 0.15;
        transform: translate(0, -20px) scale(0.7);
      }
      100% {
        opacity: 0;
        transform: translate(0, -24px) scale(0.5);
      }
    }

    .sparkle-particle {
      transform-box: fill-box;
      transform-origin: center;
      animation: sparkleAbsorb 4.5s ease-in-out infinite;
      will-change: transform, opacity;
    }
    .sp-1 { animation-delay: 0s; }
    .sp-2 { animation-delay: 1.5s; }
    .sp-3 { animation-delay: 3.0s; }

    .water-particle {
      transform-box: fill-box;
      transform-origin: center;
      animation: waterAbsorbLeft 4.5s ease-in-out infinite;
      will-change: transform, opacity;
    }
    .wp-1 { animation-delay: 0s; }
    .wp-2 { animation-delay: 1.5s; }
    .wp-3 {
      animation: waterAbsorbTop 4.5s ease-in-out infinite;
      animation-delay: 3.0s;
    }

    @media (max-width: 420px) {
      .title { font-size: 13.5px; }
      .pill { font-size: 10px; padding: 2px 6px; }
      .tag { font-size: 11px; padding: 3px 6px; }
      .svg-wrap { height: 135px; }
      .info-box { font-size: 11.5px; padding: 8px 10px; }
    }
  </style>
</head>
<body>

  <div class="container">
    <div class="grid">
      
      <div class="organ-panel active" id="cardSmall" role="button" tabindex="0" onclick="selectCard('small')">
        <div class="title">Small Intestine</div>
        <div class="pill pill-small">20 ft • Skinny &amp; Looped</div>
        <div class="svg-wrap">
          <svg viewBox="0 0 160 150">
            <defs>
              <linearGradient id="pinkGrad" x1="0%" y1="0%" x2="100%" y2="100%">
                <stop offset="0%" stop-color="#f472b6" />
                <stop offset="100%" stop-color="#db2777" />
              </linearGradient>
              <linearGradient id="bloodGrad" x1="0%" y1="0%" x2="0%" y2="100%">
                <stop offset="0%" stop-color="#ef4444" />
                <stop offset="100%" stop-color="#b91c1c" />
              </linearGradient>
            </defs>

            
            <g stroke="url(#bloodGrad)" stroke-linecap="round" fill="none">
              <path d="M 132,15 Q 135,75 130,135" stroke-width="3.5" />
              <path d="M 132,40 Q 110,36 94,44" stroke-width="2.2" />
              <path d="M 131,75 Q 112,70 98,78" stroke-width="2.2" />
              <path d="M 130,110 Q 110,105 94,112" stroke-width="2.2" />
            </g>

            
            <path d="M 30,22 
                     C 100,16 100,45 35,45 
                     C -10,45 -5,75 85,75 
                     C 115,75 105,105 35,105 
                     C -5,105 12,132 80,132" 
                  fill="none" 
                  stroke="url(#pinkGrad)" 
                  stroke-width="12" 
                  stroke-linecap="round" 
                  stroke-linejoin="round" />

            
            <g class="sparkle-particle sp-1">
              <circle cx="68" cy="44" r="4.5" fill="#d97706" />
              <polygon points="68,38 70,42 74,44 70,46 68,50 66,46 62,44 66,42" fill="#fbbf24" />
            </g>
            <g class="sparkle-particle sp-2">
              <circle cx="64" cy="74" r="4.5" fill="#d97706" />
              <polygon points="64,68 66,72 70,74 66,76 64,80 62,76 58,74 62,72" fill="#fbbf24" />
            </g>
            <g class="sparkle-particle sp-3">
              <circle cx="66" cy="106" r="4.5" fill="#d97706" />
              <polygon points="66,100 68,104 72,106 68,108 66,112 64,108 60,106 64,104" fill="#fbbf24" />
            </g>
          </svg>
        </div>
        <div class="tag tag-sparkle">✨ Absorbs Nutrients</div>
      </div>

      
      <div class="organ-panel" id="cardLarge" role="button" tabindex="0" onclick="selectCard('large')">
        <div class="title">Large Intestine</div>
        <div class="pill pill-large">5 ft • Shorter &amp; Wider</div>
        <div class="svg-wrap">
          <svg viewBox="0 0 160 150">
            <defs>
              <linearGradient id="colonGrad" x1="0%" y1="0%" x2="100%" y2="100%">
                <stop offset="0%" stop-color="#fed7aa" />
                <stop offset="100%" stop-color="#f97316" />
              </linearGradient>
            </defs>

            
            <path d="M 36,128 
                     L 36,38 
                     Q 36,24 50,24 
                     L 110,24 
                     Q 124,24 124,38 
                     L 124,115 
                     Q 124,132 106,134 
                     L 94,134 
                     L 94,142" 
                  fill="none" 
                  stroke="url(#colonGrad)" 
                  stroke-width="24" 
                  stroke-linecap="round" 
                  stroke-linejoin="round" />

            
            <path d="M 36,116 
                     L 36,38 
                     Q 36,31 48,31 
                     L 112,31 
                     Q 124,31 124,38 
                     L 124,115 
                     Q 124,130 106,132 
                     L 94,132" 
                  fill="none" 
                  stroke="#78350f" 
                  stroke-width="8" 
                  stroke-linecap="round" 
                  stroke-linejoin="round" 
                  stroke-dasharray="12 7" />

            
            <g class="water-particle wp-1">
              <ellipse cx="20" cy="65" rx="3.5" ry="5" fill="#0284c7" />
            </g>
            <g class="water-particle wp-2">
              <ellipse cx="20" cy="98" rx="3.5" ry="5" fill="#0284c7" />
            </g>
            <g class="water-particle wp-3">
              <ellipse cx="80" cy="12" rx="5" ry="3.5" fill="#0284c7" />
            </g>

            
            <circle cx="94" cy="140" r="4.5" fill="#582407" />
          </svg>
        </div>
        <div class="tag tag-water">💧 Absorbs Water</div>
      </div>
    </div>

    
    <div class="info-box" id="infoText">
      <span><strong>Small Intestine:</strong> Very long (20 ft) tube that absorbs vitamins and nutrients directly into blood vessels.</span>
    </div>
  </div>

  <script>
    const infoSmall = '<strong>Small Intestine:</strong> Very long (20 ft) tube that absorbs vitamins and nutrients directly into blood vessels.';
    const infoLarge = '<strong>Large Intestine:</strong> Shorter & wider (5 ft) tube that reabsorbs water and compacts remaining solid waste.';

    function selectCard(type) {
      const isSmall = type === 'small';
      document.getElementById('cardSmall').classList.toggle('active', isSmall);
      document.getElementById('cardLarge').classList.toggle('active', !isSmall);
      document.getElementById('infoText').innerHTML = isSmall ? infoSmall : infoLarge;
    }

    document.getElementById('cardSmall').addEventListener('keydown', (e) => {
      if (e.key === 'Enter' || e.key === ' ') { e.preventDefault(); selectCard('small'); }
    });
    document.getElementById('cardLarge').addEventListener('keydown', (e) => {
      if (e.key === 'Enter' || e.key === ' ') { e.preventDefault(); selectCard('large'); }
    });
  </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="1:1">
  <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;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
      user-select: none;
    }

    .main-stage {
      display: flex;
      flex-direction: row;
      align-items: center;
      justify-content: center;
      gap: 16px;
      width: 100%;
      max-width: 580px;
      flex: 1;
    }

    .anatomy-view {
      position: relative;
      width: 210px;
      height: 330px;
      flex-shrink: 0;
    }

    .anatomy-svg {
      width: 100%;
      height: 100%;
      overflow: visible;
    }

    .organ {
      cursor: pointer;
      transition: filter 0.3s ease, opacity 0.3s ease, stroke-width 0.3s ease;
      opacity: 0.82;
    }
    .organ:hover {
      opacity: 1;
      filter: drop-shadow(0 0 4px rgba(0,0,0,0.15));
    }
    .organ.active {
      opacity: 1;
      filter: drop-shadow(0 0 7px currentColor);
    }

    .food-bite {
      position: absolute;
      width: 24px;
      height: 24px;
      font-size: 16px;
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: 50%;
      background: #ffffff;
      box-shadow: 0 0 10px #ff3b30, 0 0 4px rgba(0,0,0,0.2);
      transform: translate(-50%, -50%);
      transition: left 0.6s cubic-bezier(0.4, 0, 0.2, 1), top 0.6s cubic-bezier(0.4, 0, 0.2, 1);
      pointer-events: none;
      z-index: 10;
    }

    .steps-list {
      display: flex;
      flex-direction: column;
      gap: 6px;
      flex: 1;
      max-width: 300px;
    }

    .step-card {
      display: flex;
      align-items: center;
      gap: 10px;
      padding: 7px 10px;
      background: #f8fafc;
      border-radius: 8px;
      cursor: pointer;
      transition: background 0.25s ease, box-shadow 0.25s ease;
      border: 1.5px solid transparent;
    }

    .step-card:hover {
      background: #f1f5f9;
    }

    .step-card.active {
      background: #ffffff;
      box-shadow: 0 2px 8px rgba(30, 41, 69, 0.1);
      border-color: var(--card-accent, #22b7ff);
    }

    .step-dot {
      width: 12px;
      height: 12px;
      border-radius: 50%;
      background: var(--card-accent, #94a3b8);
      flex-shrink: 0;
    }

    .step-text {
      display: flex;
      flex-direction: column;
      line-height: 1.2;
    }

    .step-name {
      font-size: 13px;
      font-weight: 700;
      color: #1e2945;
    }

    .step-desc {
      font-size: 12px;
      font-weight: 500;
      color: #64748b;
    }

    .step-card.active .step-desc {
      color: #334155;
      font-weight: 600;
    }

    .controls {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 10px;
      width: 100%;
      margin-top: 10px;
    }

    .ctrl-btn {
      background: #f1f5f9;
      border: none;
      color: #1e2945;
      font-size: 13px;
      font-weight: 600;
      padding: 6px 14px;
      border-radius: 6px;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      transition: background 0.2s ease, transform 0.1s ease;
    }
    .ctrl-btn:hover {
      background: #e2e8f0;
    }
    .ctrl-btn:active {
      transform: scale(0.97);
    }
    .ctrl-btn.play {
      background: #22b7ff;
      color: #ffffff;
    }
    .ctrl-btn.play:hover {
      background: #0ea5e9;
    }

    @media (max-width: 460px) {
      .main-stage {
        flex-direction: row;
        gap: 10px;
      }
      .anatomy-view {
        width: 150px;
        height: 270px;
      }
      .step-name { font-size: 12px; }
      .step-desc { font-size: 11px; }
      .step-card { padding: 5px 8px; gap: 6px; }
    }
  </style>
</head>
<body>

  <div class="main-stage">
    
    <div class="anatomy-view" id="anatomyBox">
      <svg class="anatomy-svg" viewBox="0 0 200 320" xmlns="http://www.w3.org/2000/svg">
        <defs>
          
          <linearGradient id="bodyGrad" x1="0%" y1="0%" x2="100%" y2="100%">
            <stop offset="0%" stop-color="#f1f5f9" />
            <stop offset="100%" stop-color="#e2e8f0" />
          </linearGradient>
        </defs>

        
        <g fill="url(#bodyGrad)" stroke="#cbd5e1" stroke-width="1.5">
          
          <path d="M 100,10 C 82,10 74,25 74,42 C 74,58 84,68 88,74 L 88,86 L 60,94 C 42,100 40,118 40,140 L 40,240 C 40,256 52,268 70,270 L 70,310 L 130,310 L 130,270 C 148,268 160,256 160,240 L 160,140 C 160,118 158,100 140,94 L 112,86 L 112,74 C 116,68 126,58 126,42 C 126,25 118,10 100,10 Z" />
        </g>

        

        
        <g id="organ-0" class="organ active" color="#f472b6" onclick="goToStep(0)">
          <path d="M 90,44 Q 100,52 110,44 Q 100,40 90,44 Z" fill="#f472b6" stroke="#db2777" stroke-width="2"/>
          <circle cx="100" cy="46" r="6" fill="#f472b6"/>
        </g>

        
        <g id="organ-1" class="organ" color="#fb923c" onclick="goToStep(1)">
          <path d="M 100,52 L 100,115" fill="none" stroke="#fb923c" stroke-width="6" stroke-linecap="round"/>
        </g>

        
        <g id="organ-2" class="organ" color="#fb7185" onclick="goToStep(2)">
          <path d="M 100,115 C 104,118 125,120 128,140 C 130,158 112,168 95,165 C 84,162 82,150 92,142 C 98,138 98,128 100,115 Z" fill="#fb7185" stroke="#e11d48" stroke-width="2.5" stroke-linejoin="round"/>
        </g>

        
        <g id="organ-4" class="organ" color="#4ade80" onclick="goToStep(4)">
          
          <path d="M 72,216 L 72,170 C 72,160 82,158 100,158 C 118,158 128,160 128,170 L 128,216" fill="none" stroke="#4ade80" stroke-width="12" stroke-linecap="round" stroke-linejoin="round"/>
          <path d="M 72,216 L 72,170 C 72,160 82,158 100,158 C 118,158 128,160 128,170 L 128,216" fill="none" stroke="#22c55e" stroke-width="2" stroke-dasharray="3,4" stroke-linecap="round" stroke-linejoin="round"/>
        </g>

        
        <g id="organ-3" class="organ" color="#eab308" onclick="goToStep(3)">
          <path d="M 94,165 Q 108,172 108,182 Q 88,185 88,195 Q 112,198 112,208 Q 90,212 76,216" fill="none" stroke="#fde047" stroke-width="8" stroke-linecap="round" stroke-linejoin="round"/>
          <path d="M 94,165 Q 108,172 108,182 Q 88,185 88,195 Q 112,198 112,208 Q 90,212 76,216" fill="none" stroke="#ca8a04" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"/>
        </g>

        
        <g id="organ-5" class="organ" color="#c084fc" onclick="goToStep(5)">
          <path d="M 128,216 C 128,230 102,234 100,250" fill="none" stroke="#c084fc" stroke-width="7" stroke-linecap="round"/>
          <circle cx="100" cy="252" r="4.5" fill="#a855f7"/>
        </g>
      </svg>

      
      <div id="foodBite" class="food-bite">🍎</div>
    </div>

    
    <div class="steps-list">
      <div class="step-card active" style="--card-accent: #f472b6;" onclick="goToStep(0)">
        <div class="step-dot"></div>
        <div class="step-text">
          <span class="step-name">1. Mouth</span>
          <span class="step-desc">Chews food</span>
        </div>
      </div>

      <div class="step-card" style="--card-accent: #fb923c;" onclick="goToStep(1)">
        <div class="step-dot"></div>
        <div class="step-text">
          <span class="step-name">2. Esophagus</span>
          <span class="step-desc">Pushes down</span>
        </div>
      </div>

      <div class="step-card" style="--card-accent: #fb7185;" onclick="goToStep(2)">
        <div class="step-dot"></div>
        <div class="step-text">
          <span class="step-name">3. Stomach</span>
          <span class="step-desc">Mashes food</span>
        </div>
      </div>

      <div class="step-card" style="--card-accent: #eab308;" onclick="goToStep(3)">
        <div class="step-dot"></div>
        <div class="step-text">
          <span class="step-name">4. Small Intestine</span>
          <span class="step-desc">Takes nutrients</span>
        </div>
      </div>

      <div class="step-card" style="--card-accent: #4ade80;" onclick="goToStep(4)">
        <div class="step-dot"></div>
        <div class="step-text">
          <span class="step-name">5. Large Intestine</span>
          <span class="step-desc">Takes water</span>
        </div>
      </div>

      <div class="step-card" style="--card-accent: #c084fc;" onclick="goToStep(5)">
        <div class="step-dot"></div>
        <div class="step-text">
          <span class="step-name">6. Rectum</span>
          <span class="step-desc">Holds waste</span>
        </div>
      </div>
    </div>
  </div>

  
  <div class="controls">
    <button class="ctrl-btn" onclick="prevStep()">◀ Back</button>
    <button id="playBtn" class="ctrl-btn play" onclick="togglePlay()">⏸ Pause</button>
    <button class="ctrl-btn" onclick="nextStep()">Next ▶</button>
  </div>

  <script>
    // Relative coordinates (% within anatomyBox) for food bite positions at each organ
    const organPositions = [
      { x: 50.0, y: 14.5 }, // 0: Mouth (100, 46) / (200, 320)
      { x: 50.0, y: 26.5 }, // 1: Esophagus (100, 85)
      { x: 55.5, y: 44.5 }, // 2: Stomach (111, 142)
      { x: 49.0, y: 59.0 }, // 3: Small Intestine (98, 189)
      { x: 64.0, y: 59.0 }, // 4: Large Intestine (128, 189)
      { x: 50.0, y: 78.5 }  // 5: Rectum (100, 251)
    ];

    let currentStep = 0;
    let isPlaying = true;
    let autoTimer = null;
    const STEP_DURATION = 3200;

    const cards = document.querySelectorAll('.step-card');
    const organs = document.querySelectorAll('.organ');
    const foodBite = document.getElementById('foodBite');
    const playBtn = document.getElementById('playBtn');

    function updateView() {
      // Update Organ Path Highlights
      organs.forEach((org, idx) => {
        if (idx === currentStep) {
          org.classList.add('active');
        } else {
          org.classList.remove('active');
        }
      });

      // Update Step Card Highlight
      cards.forEach((card, idx) => {
        if (idx === currentStep) {
          card.classList.add('active');
        } else {
          card.classList.remove('active');
        }
      });

      // Update Food Position
      const pos = organPositions[currentStep];
      foodBite.style.left = pos.x + '%';
      foodBite.style.top = pos.y + '%';
    }

    function goToStep(idx) {
      currentStep = idx;
      updateView();
      if (isPlaying) {
        resetTimer();
      }
    }

    function nextStep() {
      currentStep = (currentStep + 1) % organPositions.length;
      updateView();
      if (isPlaying) resetTimer();
    }

    function prevStep() {
      currentStep = (currentStep - 1 + organPositions.length) % organPositions.length;
      updateView();
      if (isPlaying) resetTimer();
    }

    function resetTimer() {
      clearInterval(autoTimer);
      if (isPlaying) {
        autoTimer = setInterval(() => {
          currentStep = (currentStep + 1) % organPositions.length;
          updateView();
        }, STEP_DURATION);
      }
    }

    function togglePlay() {
      isPlaying = !isPlaying;
      if (isPlaying) {
        playBtn.textContent = '⏸ Pause';
        playBtn.classList.add('play');
        resetTimer();
      } else {
        playBtn.textContent = '▶ Play';
        playBtn.classList.remove('play');
        clearInterval(autoTimer);
      }
    }

    // Initialize
    updateView();
    resetTimer();
  </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="1:1">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      width: 100%;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      padding: 12px 16px;
      min-height: 100%;
      user-select: none;
    }

    /* Controls Bar */
    .controls {
      display: flex;
      gap: 8px;
      margin-bottom: 8px;
      flex-wrap: wrap;
      justify-content: center;
      width: 100%;
      max-width: 420px;
    }

    .btn {
      background: #f1f5f9;
      border: 1px solid #cbd5e1;
      color: #334155;
      padding: 6px 14px;
      border-radius: 20px;
      font-size: 14px;
      font-weight: 600;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 6px;
      transition: background-color 0.2s, border-color 0.2s, color 0.2s;
    }
    .btn:hover {
      background: #e2e8f0;
    }
    .btn.active {
      background: #0284c7;
      color: #ffffff;
      border-color: #0284c7;
    }

    /* Main Stage */
    .stage {
      position: relative;
      width: 100%;
      max-width: 380px;
      height: 380px;
      display: flex;
      justify-content: center;
      align-items: center;
    }

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

    /* Indicators / Stepper */
    .stepper {
      display: flex;
      align-items: center;
      gap: 12px;
      margin-top: 6px;
    }
    .step-btn {
      background: #f8fafc;
      border: 1px solid #cbd5e1;
      width: 32px;
      height: 32px;
      border-radius: 50%;
      font-size: 14px;
      font-weight: bold;
      color: #334155;
      cursor: pointer;
      display: flex;
      align-items: center;
      justify-content: center;
    }
    .step-dots {
      display: flex;
      gap: 6px;
    }
    .dot {
      width: 10px;
      height: 10px;
      border-radius: 50%;
      background: #cbd5e1;
      cursor: pointer;
      transition: background-color 0.3s;
    }
    .dot.active {
      background: #0284c7;
    }
  </style>
</head>
<body>

  
  <div class="controls">
    <button id="btnStanding" class="btn active" onclick="setMode('standing')">🧍 Standing</button>
    <button id="btnInverted" class="btn" onclick="setMode('upsideDown')">🙃 Upside Down</button>
  </div>

  
  <div class="stage">
    <svg viewBox="0 0 340 380">
      <defs>
        
        <linearGradient id="pinkWall" x1="0%" y1="0%" x2="100%" y2="0%">
          <stop offset="0%" stop-color="#fda4af" />
          <stop offset="50%" stop-color="#ffe4e6" />
          <stop offset="100%" stop-color="#fda4af" />
        </linearGradient>
        <radialGradient id="foodGrad" cx="35%" cy="35%" r="65%">
          <stop offset="0%" stop-color="#86efac" />
          <stop offset="70%" stop-color="#22c55e" />
          <stop offset="100%" stop-color="#15803d" />
        </radialGradient>
      </defs>

      
      <g id="topEndpoint">
        <text id="topLabel" x="170" y="24" text-anchor="middle" font-size="14" font-weight="bold" fill="#475569">👄 Throat</text>
      </g>
      <g id="bottomEndpoint">
        <text id="bottomLabel" x="170" y="366" text-anchor="middle" font-size="14" font-weight="bold" fill="#475569">🫄 Stomach</text>
      </g>

      
      <g id="gravityTag" opacity="0.85">
        <rect x="272" y="170" width="58" height="42" rx="6" fill="#f1f5f9" stroke="#cbd5e1" stroke-width="1"/>
        <text x="301" y="187" text-anchor="middle" font-size="11" font-weight="600" fill="#64748b">Gravity</text>
        <text x="301" y="204" text-anchor="middle" font-size="14" font-weight="bold" fill="#64748b">⬇</text>
      </g>

      
      
      <path id="leftWall" fill="url(#pinkWall)" stroke="#f43f5e" stroke-width="2.5" />
      <path id="rightWall" fill="url(#pinkWall)" stroke="#f43f5e" stroke-width="2.5" />

      
      <circle id="foodBall" r="21" fill="url(#foodGrad)" stroke="#166534" stroke-width="2" />

      
      <g id="squeezeGroup">
        <rect id="squeezeBg" x="22" y="0" width="76" height="24" rx="12" fill="#0284c7" />
        <text id="squeezeText" x="60" y="16" text-anchor="middle" font-size="12" font-weight="bold" fill="#ffffff">Squeeze!</text>
        
        <path id="arrLeftIn" fill="#0284c7" d="M 108 0 L 126 0 L 126 -5 L 136 0 L 126 5 L 126 0 Z" />
        <path id="arrRightIn" fill="#0284c7" d="M 232 0 L 214 0 L 214 -5 L 204 0 L 214 5 L 214 0 Z" />
      </g>

      
      <g id="openGroup">
        <rect id="openBg" x="22" y="0" width="76" height="24" rx="12" fill="#0d9488" />
        <text id="openText" x="60" y="16" text-anchor="middle" font-size="12" font-weight="bold" fill="#ffffff">Open!</text>
        
        <path id="arrLeftOut" fill="#0d9488" d="M 132 0 L 116 0 L 116 -5 L 106 0 L 116 5 L 116 0 Z" />
        <path id="arrRightOut" fill="#0d9488" d="M 208 0 L 224 0 L 224 -5 L 234 0 L 224 5 L 224 0 Z" />
      </g>
    </svg>
  </div>

  
  <div class="stepper">
    <button class="step-btn" onclick="prevStep()">‹</button>
    <div class="step-dots">
      <div class="dot active" onclick="goToStep(0)"></div>
      <div class="dot" onclick="goToStep(1)"></div>
      <div class="dot" onclick="goToStep(2)"></div>
      <div class="dot" onclick="goToStep(3)"></div>
    </div>
    <button class="step-btn" onclick="nextStep()">›</button>
  </div>

  <script>
    let mode = 'standing'; // 'standing' or 'upsideDown'
    let currentStep = 0;
    const totalSteps = 4;
    let timer = null;

    // Y positions of the ball for each step (top to bottom: 42 to 345)
    const yStanding = [80, 150, 225, 300];
    const yInverted = [300, 225, 150, 80];

    function updateView() {
      // Endpoint labels
      const topLabel = document.getElementById('topLabel');
      const bottomLabel = document.getElementById('bottomLabel');
      
      if (mode === 'standing') {
        topLabel.textContent = '👄 Throat';
        bottomLabel.textContent = '🫄 Stomach';
      } else {
        topLabel.textContent = '🫄 Stomach';
        bottomLabel.textContent = '👄 Throat';
      }

      // Ball Y coordinate
      const ballY = (mode === 'standing') ? yStanding[currentStep] : yInverted[currentStep];
      const ballX = 170;

      const foodBall = document.getElementById('foodBall');
      foodBall.setAttribute('cx', ballX);
      foodBall.setAttribute('cy', ballY);

      // Tube Path Computation
      // Fixed top Y=40, bottom Y=340. Normal tube width = 50 (left=145, right=195)
      // At squeeze: width constricts to 20 (left=160, right=180)
      // At ball: width expands to 52 (left=144, right=196)
      // At open (ahead): width opens to 60 (left=140, right=200)

      const isDown = (mode === 'standing');
      const squeezeY = isDown ? ballY - 45 : ballY + 45;
      const openY = isDown ? ballY + 45 : ballY - 45;

      // Sample tube profile at 12 key heights
      const sampleYs = [40, 70, 105, 140, 175, 210, 245, 280, 315, 345];
      let leftPts = [];
      let rightPts = [];

      for (let y of sampleYs) {
        let halfWidth = 26; // normal half-width (total 52)
        
        // Distance to ball, squeeze, open
        const distBall = Math.abs(y - ballY);
        const distSqueeze = Math.abs(y - squeezeY);
        const distOpen = Math.abs(y - openY);

        if (distBall < 30) {
          halfWidth = 28 - (distBall / 30) * 2;
        } else if (distSqueeze < 35) {
          halfWidth = 13 + (distSqueeze / 35) * 13; // pinched to 13 (width 26)
        } else if (distOpen < 35) {
          halfWidth = 33 - (distOpen / 35) * 7; // relaxed to 33 (width 66)
        }

        leftPts.push({ x: 170 - halfWidth, y: y });
        rightPts.push({ x: 170 + halfWidth, y: y });
      }

      // Build left wall path
      let dLeft = `M ${leftPts[0].x - 12} ${leftPts[0].y} L ${leftPts[0].x} ${leftPts[0].y} `;
      for (let i = 1; i < leftPts.length; i++) {
        dLeft += `L ${leftPts[i].x} ${leftPts[i].y} `;
      }
      dLeft += `L ${leftPts[leftPts.length - 1].x - 12} ${leftPts[leftPts.length - 1].y} Z`;

      // Build right wall path
      let dRight = `M ${rightPts[0].x + 12} ${rightPts[0].y} L ${rightPts[0].x} ${rightPts[0].y} `;
      for (let i = 1; i < rightPts.length; i++) {
        dRight += `L ${rightPts[i].x} ${rightPts[i].y} `;
      }
      dRight += `L ${rightPts[rightPts.length - 1].x + 12} ${rightPts[rightPts.length - 1].y} Z`;

      document.getElementById('leftWall').setAttribute('d', dLeft);
      document.getElementById('rightWall').setAttribute('d', dRight);

      // Position Annotations
      const squeezeGroup = document.getElementById('squeezeGroup');
      const openGroup = document.getElementById('openGroup');

      // Hide squeeze if outside bounds
      if (squeezeY >= 40 && squeezeY <= 345) {
        squeezeGroup.setAttribute('opacity', '1');
        squeezeGroup.setAttribute('transform', `translate(0, ${squeezeY})`);
        document.getElementById('squeezeBg').setAttribute('y', -12);
        document.getElementById('squeezeText').setAttribute('y', 5);
      } else {
        squeezeGroup.setAttribute('opacity', '0');
      }

      // Hide open if outside bounds
      if (openY >= 40 && openY <= 345) {
        openGroup.setAttribute('opacity', '1');
        openGroup.setAttribute('transform', `translate(0, ${openY})`);
        document.getElementById('openBg').setAttribute('y', -12);
        document.getElementById('openText').setAttribute('y', 5);
      } else {
        openGroup.setAttribute('opacity', '0');
      }

      // Update dots
      document.querySelectorAll('.dot').forEach((dot, idx) => {
        dot.classList.toggle('active', idx === currentStep);
      });
    }

    function setMode(newMode) {
      mode = newMode;
      document.getElementById('btnStanding').classList.toggle('active', mode === 'standing');
      document.getElementById('btnInverted').classList.toggle('active', mode === 'upsideDown');
      currentStep = 0;
      updateView();
      restartTimer();
    }

    function nextStep() {
      currentStep = (currentStep + 1) % totalSteps;
      updateView();
      restartTimer();
    }

    function prevStep() {
      currentStep = (currentStep - 1 + totalSteps) % totalSteps;
      updateView();
      restartTimer();
    }

    function goToStep(idx) {
      currentStep = idx;
      updateView();
      restartTimer();
    }

    function restartTimer() {
      if (timer) clearInterval(timer);
      timer = setInterval(() => {
        currentStep = (currentStep + 1) % totalSteps;
        updateView();
      }, 3000);
    }

    // Initialize
    updateView();
    restartTimer();
  </script>
</body>
</html>

science.ks3.y1.t2.s1

Aligned learning resources

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