<!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;
      gap: 10px;
      user-select: none;
    }

    /* Controls Bar */
    .controls {
      display: flex;
      justify-content: space-between;
      align-items: center;
      gap: 8px;
    }

    .btn-group {
      display: flex;
      gap: 6px;
      background: #f1f5f9;
      padding: 3px;
      border-radius: 8px;
    }

    .btn {
      background: transparent;
      border: none;
      outline: none;
      padding: 5px 12px;
      font-size: 13px;
      font-weight: 600;
      color: #64748b;
      cursor: pointer;
      border-radius: 6px;
      transition: all 0.2s ease;
    }

    .btn.active {
      background: #ffffff;
      color: #1e2945;
      box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    }

    .play-btn {
      background: #22b7ff;
      color: #ffffff;
      border: none;
      border-radius: 8px;
      padding: 5px 14px;
      font-size: 13px;
      font-weight: 600;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 4px;
      transition: opacity 0.2s ease;
    }

    .play-btn:active {
      opacity: 0.85;
    }

    /* Panels */
    .panel {
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 10px 12px 14px;
      display: flex;
      flex-direction: column;
      gap: 6px;
      position: relative;
      overflow: hidden;
    }

    .panel-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-size: 13px;
      font-weight: 700;
      color: #1e2945;
    }

    .panel-tag {
      font-size: 11px;
      font-weight: 600;
      padding: 2px 8px;
      border-radius: 12px;
      background: #e0f2fe;
      color: #0284c7;
    }

    .stage {
      position: relative;
      height: 90px;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    /* Molecules & Atoms */
    .molecule-track {
      position: relative;
      width: 100%;
      max-width: 420px;
      height: 100%;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .monomer {
      width: 82px;
      height: 44px;
      background: #ffffff;
      border: 2px solid #cbd5e1;
      border-radius: 22px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 13px;
      font-weight: 700;
      color: #1e2945;
      position: absolute;
      transition: transform 0.8s cubic-bezier(0.4, 0, 0.2, 1), border-color 0.4s ease;
      z-index: 2;
      box-shadow: 0 2px 4px rgba(0,0,0,0.04);
    }

    /* Functional groups */
    .group {
      position: absolute;
      font-size: 12px;
      font-weight: 800;
      padding: 2px 5px;
      border-radius: 4px;
      transition: all 0.8s cubic-bezier(0.4, 0, 0.2, 1);
      z-index: 3;
    }

    .group-oh {
      color: #0284c7;
      background: #e0f2fe;
    }

    .group-h {
      color: #0284c7;
      background: #e0f2fe;
    }

    /* Water Droplet */
    .water-bubble {
      position: absolute;
      width: 44px;
      height: 44px;
      background: radial-gradient(circle at 35% 35%, #7dd3fc, #0284c7);
      border-radius: 50% 50% 50% 10%;
      transform: rotate(-45deg);
      display: flex;
      align-items: center;
      justify-content: center;
      color: #ffffff;
      font-weight: 800;
      font-size: 13px;
      box-shadow: 0 4px 10px rgba(2, 132, 199, 0.35);
      transition: all 0.8s cubic-bezier(0.4, 0, 0.2, 1);
      z-index: 4;
    }

    .water-text {
      transform: rotate(45deg);
    }

    /* Bond Line */
    .bond-bridge {
      position: absolute;
      height: 4px;
      background: #22b7ff;
      border-radius: 2px;
      transition: all 0.8s cubic-bezier(0.4, 0, 0.2, 1);
      z-index: 1;
      opacity: 0;
      width: 0;
    }

    /* CONDENSATION POSITIONS */
    /* Step 0: Initial Separate */
    .cond-s0 .m1 { transform: translateX(-95px); }
    .cond-s0 .m2 { transform: translateX(95px); }
    .cond-s0 .oh { transform: translateX(-40px); opacity: 1; }
    .cond-s0 .h  { transform: translateX(40px); opacity: 1; }
    .cond-s0 .water { transform: translateY(-40px) scale(0) rotate(-45deg); opacity: 0; }
    .cond-s0 .bond-bridge { width: 0; opacity: 0; }

    /* Step 1: Reacted Dimer + Released Water */
    .cond-s1 .m1 { transform: translateX(-42px); border-color: #22b7ff; }
    .cond-s1 .m2 { transform: translateX(42px); border-color: #22b7ff; }
    .cond-s1 .oh { transform: translateY(-38px) scale(0.2); opacity: 0; }
    .cond-s1 .h  { transform: translateY(-38px) scale(0.2); opacity: 0; }
    .cond-s1 .water { transform: translateY(-24px) scale(1) rotate(-45deg); opacity: 1; }
    .cond-s1 .bond-bridge { width: 30px; opacity: 1; }

    /* HYDROLYSIS POSITIONS */
    /* Step 0: Joined Polymer + Incoming Water */
    .hydr-s0 .m1 { transform: translateX(-42px); border-color: #22b7ff; }
    .hydr-s0 .m2 { transform: translateX(42px); border-color: #22b7ff; }
    .hydr-s0 .water { transform: translateY(-24px) scale(1) rotate(-45deg); opacity: 1; }
    .hydr-s0 .oh { transform: translateY(-38px) scale(0.2); opacity: 0; }
    .hydr-s0 .h  { transform: translateY(-38px) scale(0.2); opacity: 0; }
    .hydr-s0 .bond-bridge { width: 30px; opacity: 1; }

    /* Step 1: Split Monomers + Reabsorbed Water */
    .hydr-s1 .m1 { transform: translateX(-95px); border-color: #cbd5e1; }
    .hydr-s1 .m2 { transform: translateX(95px); border-color: #cbd5e1; }
    .hydr-s1 .water { transform: translateY(0px) scale(0) rotate(-45deg); opacity: 0; }
    .hydr-s1 .oh { transform: translateX(-40px) scale(1); opacity: 1; }
    .hydr-s1 .h  { transform: translateX(40px) scale(1); opacity: 1; }
    .hydr-s1 .bond-bridge { width: 0; opacity: 0; }
  </style>
</head>
<body>

  
  <div class="controls">
    <div class="btn-group">
      <button class="btn active" id="btnBefore" onclick="setStep(0)">Before</button>
      <button class="btn" id="btnAfter" onclick="setStep(1)">After</button>
    </div>
    <button class="play-btn" id="playBtn" onclick="toggleAuto()">
      <span id="playIcon">⏸</span> Auto
    </button>
  </div>

  
  <div class="panel">
    <div class="panel-header">
      <span>Condensation (Synthesis)</span>
      <span class="panel-tag">+ Releases H₂O</span>
    </div>
    <div class="stage">
      <div id="condTrack" class="molecule-track cond-s0">
        <div class="monomer m1">Monomer</div>
        <span class="group group-oh oh">-OH</span>
        <div class="bond-bridge"></div>
        <div class="water-bubble water">
          <span class="water-text">H₂O</span>
        </div>
        <span class="group group-h h">H-</span>
        <div class="monomer m2">Monomer</div>
      </div>
    </div>
  </div>

  
  <div class="panel">
    <div class="panel-header">
      <span>Hydrolysis (Breakdown)</span>
      <span class="panel-tag">- Uses H₂O</span>
    </div>
    <div class="stage">
      <div id="hydrTrack" class="molecule-track hydr-s0">
        <div class="monomer m1">Monomer</div>
        <span class="group group-oh oh">-OH</span>
        <div class="bond-bridge"></div>
        <div class="water-bubble water">
          <span class="water-text">H₂O</span>
        </div>
        <span class="group group-h h">H-</span>
        <div class="monomer m2">Monomer</div>
      </div>
    </div>
  </div>

  <script>
    let currentStep = 0;
    let autoPlaying = true;
    let timer = null;

    const condTrack = document.getElementById('condTrack');
    const hydrTrack = document.getElementById('hydrTrack');
    const btnBefore = document.getElementById('btnBefore');
    const btnAfter = document.getElementById('btnAfter');
    const playIcon = document.getElementById('playIcon');

    function applyState(step) {
      currentStep = step;
      if (step === 0) {
        condTrack.className = 'molecule-track cond-s0';
        hydrTrack.className = 'molecule-track hydr-s0';
        btnBefore.classList.add('active');
        btnAfter.classList.remove('active');
      } else {
        condTrack.className = 'molecule-track cond-s1';
        hydrTrack.className = 'molecule-track hydr-s1';
        btnBefore.classList.remove('active');
        btnAfter.classList.add('active');
      }
    }

    function setStep(step) {
      if (autoPlaying) {
        toggleAuto();
      }
      applyState(step);
    }

    function stepCycle() {
      applyState(currentStep === 0 ? 1 : 0);
    }

    function startAuto() {
      autoPlaying = true;
      playIcon.textContent = '⏸';
      timer = setInterval(stepCycle, 3200);
    }

    function stopAuto() {
      autoPlaying = false;
      playIcon.textContent = '▶';
      clearInterval(timer);
    }

    function toggleAuto() {
      if (autoPlaying) {
        stopAuto();
      } else {
        startAuto();
      }
    }

    // Initialize auto cycle
    startAuto();
  </script>
</body>
</html>

Synthesis and Breakdown of Carbohydrates, Lipids, and Proteins

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Condensation of Alpha-Glucose</title>
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      width: 100%;
      min-height: 100vh;
      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: center;
      padding: 10px 12px;
      overflow-x: hidden;
      user-select: none;
    }

    .diagram-container {
      width: 100%;
      max-width: 560px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 8px;
    }

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

    svg {
      width: 100%;
      height: auto;
      max-height: 310px;
      display: block;
    }

    /* Stepper Controls */
    .controls {
      display: flex;
      flex-wrap: wrap;
      align-items: center;
      justify-content: center;
      gap: 6px;
      width: 100%;
      padding: 4px 0;
    }

    .step-btn {
      background: #f1f5f9;
      border: 1px solid #cbd5e1;
      color: #1e2945;
      padding: 6px 12px;
      border-radius: 18px;
      font-size: 12px;
      font-weight: 600;
      cursor: pointer;
      white-space: nowrap;
      transition: background 0.2s ease, color 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
    }

    .step-btn:hover {
      background: #e2e8f0;
    }

    .step-btn.active {
      background: #22b7ff;
      color: #ffffff;
      border-color: #22b7ff;
      box-shadow: 0 2px 8px rgba(34, 183, 255, 0.35);
    }

    .play-btn {
      width: 30px;
      height: 30px;
      flex-shrink: 0;
      border-radius: 50%;
      border: 1px solid #cbd5e1;
      background: #ffffff;
      display: flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      font-size: 11px;
      color: #1e2945;
      transition: background 0.2s ease;
    }
    .play-btn:hover {
      background: #f1f5f9;
    }
    .play-btn:active {
      background: #e2e8f0;
    }

    /* Animated SVG Elements */
    .highlight-glow {
      transition: opacity 0.4s ease;
    }
    .water-molecule {
      transition: transform 0.6s cubic-bezier(0.34, 1.56, 0.64, 1), opacity 0.5s ease;
    }
    .glycosidic-bridge {
      transition: opacity 0.5s ease;
    }
    .reactants-oh {
      transition: opacity 0.4s ease, transform 0.4s ease;
    }
    .mol-label {
      font-size: 13px;
      font-weight: 700;
      fill: #1e2945;
      text-anchor: middle;
    }
    .carbon-tag {
      font-size: 13px;
      font-weight: 800;
      fill: #1e2945;
    }
    .atom-text {
      font-size: 13px;
      font-weight: 700;
      font-family: inherit;
    }
    .badge-text {
      font-size: 12px;
      font-weight: 700;
      fill: #22b7ff;
      text-anchor: middle;
    }

    @media (max-width: 380px) {
      .step-btn {
        padding: 5px 8px;
        font-size: 11px;
      }
      .play-btn {
        width: 28px;
        height: 28px;
      }
    }
  </style>
</head>
<body>

  <div class="diagram-container">
    <div class="diagram-area">
      <svg viewBox="0 0 540 250" aria-label="Condensation of Alpha Glucose into Maltose">
        <defs>
          <radialGradient id="waterGlow" cx="50%" cy="50%" r="50%">
            <stop offset="0%" stop-color="#22b7ff" stop-opacity="0.25"/>
            <stop offset="100%" stop-color="#22b7ff" stop-opacity="0"/>
          </radialGradient>
          <filter id="shadow" x="-20%" y="-20%" width="140%" height="140%">
            <feDropShadow dx="0" dy="2" stdDeviation="3" flood-color="#1e2945" flood-opacity="0.12"/>
          </filter>
        </defs>

        
        <g id="leftGlucose" transform="translate(48, 48)">
          <polygon points="50,20 110,20 140,70 110,120 50,120 20,70" fill="#f8fafc" stroke="#94a3b8" stroke-width="2.5" stroke-linejoin="round" />
          
          <circle cx="110" cy="20" r="10" fill="#ffffff" stroke="#94a3b8" stroke-width="2" />
          <text x="110" y="24" text-anchor="middle" class="atom-text" fill="#64748b" font-size="11">O</text>
          
          
          <circle cx="132" cy="56" r="8" fill="#e2e8f0"/>
          <text x="132" y="60" text-anchor="middle" class="carbon-tag">1</text>

          
          <text x="80" y="145" class="mol-label">α-Glucose</text>

          
          <line x1="20" y1="70" x2="2" y2="70" stroke="#cbd5e1" stroke-width="2"/>
          <text x="-3" y="74" text-anchor="end" class="atom-text" fill="#94a3b8" font-size="12">HO</text>
        </g>

        
        <g id="rightGlucose" transform="translate(332, 48)">
          <polygon points="50,20 110,20 140,70 110,120 50,120 20,70" fill="#f8fafc" stroke="#94a3b8" stroke-width="2.5" stroke-linejoin="round" />
          
          <circle cx="110" cy="20" r="10" fill="#ffffff" stroke="#94a3b8" stroke-width="2" />
          <text x="110" y="24" text-anchor="middle" class="atom-text" fill="#64748b" font-size="11">O</text>
          
          
          <circle cx="28" cy="56" r="8" fill="#e2e8f0"/>
          <text x="28" y="60" text-anchor="middle" class="carbon-tag">4</text>

          
          <text x="80" y="145" class="mol-label">α-Glucose</text>

          
          <line x1="140" y1="70" x2="158" y2="70" stroke="#cbd5e1" stroke-width="2"/>
          <text x="162" y="74" class="atom-text" fill="#94a3b8" font-size="12">OH</text>
        </g>

        
        <g id="reactantsGroup">
          
          <ellipse id="hlReactants" cx="270" cy="118" rx="66" ry="30" fill="url(#waterGlow)" stroke="#22b7ff" stroke-width="1.5" stroke-dasharray="4,4" opacity="1" class="highlight-glow"/>

          
          <g id="leftOH" class="reactants-oh">
            <line x1="188" y1="118" x2="220" y2="118" stroke="#22b7ff" stroke-width="2.5"/>
            <rect x="220" y="105" width="28" height="26" rx="13" fill="#e0f2fe" stroke="#22b7ff" stroke-width="1.5"/>
            <text x="234" y="122" text-anchor="middle" class="atom-text" fill="#0284c7">OH</text>
          </g>

          
          <g id="rightH" class="reactants-oh">
            <line x1="352" y1="118" x2="318" y2="118" stroke="#22b7ff" stroke-width="2.5"/>
            <circle cx="306" cy="118" r="13" fill="#e0f2fe" stroke="#22b7ff" stroke-width="1.5"/>
            <text x="306" y="122" text-anchor="middle" class="atom-text" fill="#0284c7">H</text>
          </g>
        </g>

        
        <g id="leavingWater" class="water-molecule" style="transform: translateY(12px); opacity: 0;">
          <circle cx="270" cy="34" r="20" fill="#ffffff" stroke="#22b7ff" stroke-width="2" filter="url(#shadow)"/>
          <text x="270" y="39" text-anchor="middle" class="atom-text" fill="#0284c7" font-weight="800">H₂O</text>
          <line x1="270" y1="80" x2="270" y2="60" stroke="#22b7ff" stroke-width="2" stroke-dasharray="3,3"/>
          <polygon points="270,56 265,64 275,64" fill="#22b7ff"/>
          <text x="270" y="96" class="badge-text">+ H₂O Released</text>
        </g>

        
        <g id="bondBridge" class="glycosidic-bridge" opacity="0">
          
          <polyline points="188,118 270,140 352,118" fill="none" stroke="#22b7ff" stroke-width="3" stroke-linecap="round" stroke-linejoin="round"/>
          <circle cx="270" cy="140" r="13" fill="#ffffff" stroke="#22b7ff" stroke-width="2.5"/>
          <text x="270" y="144" text-anchor="middle" class="atom-text" fill="#0284c7" font-weight="800">O</text>
          
          
          <text x="270" y="176" class="badge-text" font-size="12">1,4-Glycosidic Bond</text>
          <text x="270" y="214" class="mol-label" font-size="15" fill="#1e2945">Maltose</text>
        </g>
      </svg>
    </div>

    
    <div class="controls">
      <button id="playBtn" class="play-btn" aria-label="Play or pause auto-advance">▶</button>
      <button class="step-btn active" data-step="0">1. Glucose Pair</button>
      <button class="step-btn" data-step="1">2. Water Leaves</button>
      <button class="step-btn" data-step="2">3. Glycosidic Bond</button>
    </div>
  </div>

  <script>
    const hlReactants = document.getElementById('hlReactants');
    const leftOH = document.getElementById('leftOH');
    const rightH = document.getElementById('rightH');
    const leavingWater = document.getElementById('leavingWater');
    const bondBridge = document.getElementById('bondBridge');
    const playBtn = document.getElementById('playBtn');
    const stepBtns = Array.from(document.querySelectorAll('.step-btn'));

    let currentStep = 0;
    let autoPlayTimer = null;

    function renderStep(step) {
      currentStep = step;

      stepBtns.forEach((btn, idx) => {
        btn.classList.toggle('active', idx === step);
      });

      if (step === 0) {
        // Step 1: Highlighting reactants
        hlReactants.style.opacity = '1';
        leftOH.style.opacity = '1';
        leftOH.style.transform = 'translate(0, 0)';
        rightH.style.opacity = '1';
        rightH.style.transform = 'translate(0, 0)';
        
        leavingWater.style.opacity = '0';
        leavingWater.style.transform = 'translateY(12px)';
        
        bondBridge.style.opacity = '0';
      } else if (step === 1) {
        // Step 2: Water leaves
        hlReactants.style.opacity = '0';
        leftOH.style.opacity = '0';
        leftOH.style.transform = 'translate(8px, -14px)';
        rightH.style.opacity = '0';
        rightH.style.transform = 'translate(-8px, -14px)';
        
        leavingWater.style.opacity = '1';
        leavingWater.style.transform = 'translateY(0px)';
        
        bondBridge.style.opacity = '0.35';
      } else if (step === 2) {
        // Step 3: Glycosidic bond established
        hlReactants.style.opacity = '0';
        leftOH.style.opacity = '0';
        rightH.style.opacity = '0';
        
        leavingWater.style.opacity = '1';
        leavingWater.style.transform = 'translateY(0px)';
        
        bondBridge.style.opacity = '1';
      }
    }

    function nextStep() {
      const next = (currentStep + 1) % 3;
      renderStep(next);
    }

    function toggleAutoPlay() {
      if (autoPlayTimer) {
        clearInterval(autoPlayTimer);
        autoPlayTimer = null;
        playBtn.textContent = '▶';
      } else {
        playBtn.textContent = '⏸';
        autoPlayTimer = setInterval(nextStep, 3000);
      }
    }

    stepBtns.forEach((btn, idx) => {
      btn.addEventListener('click', () => {
        if (autoPlayTimer) toggleAutoPlay();
        renderStep(idx);
      });
    });

    playBtn.addEventListener('click', toggleAutoPlay);

    // Initial render
    renderStep(0);
  </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="16:10">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      width: 100%;
      height: 100%;
      background: #f8f9fa;
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      padding: 12px;
      user-select: none;
      -webkit-user-select: none;
    }

    .controls {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      margin-bottom: 6px;
      z-index: 10;
    }

    .step-btn {
      padding: 6px 14px;
      font-size: 13px;
      font-weight: 600;
      border-radius: 20px;
      border: 1px solid #d1d5db;
      background: #ffffff;
      color: #4b5563;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      box-shadow: 0 1px 2px rgba(0,0,0,0.05);
      transition: all 0.2s ease;
    }

    .step-btn.active {
      background: #0284c7;
      color: #ffffff;
      border-color: #0284c7;
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<body>

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    <button id="btn2" class="step-btn" onclick="setStep(1)">2. Dipeptide Formed</button>
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</html>

<!DOCTYPE html>
<html lang="en">
<head>
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<body>

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    <button class="step-btn" id="btn1" onclick="setStep(1)">2. Condensation (−3 H₂O)</button>
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      </g>

      
      <text x="310" y="355" text-anchor="middle" font-family="system-ui, sans-serif" font-size="16" font-weight="700" fill="#0284c7">
        1 Triglyceride Molecule + 3 H₂O
      </text>
    </g>

    
    <defs>
      <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 L 8 5 L 0 9 z" fill="#0284c7"/>
      </marker>
    </defs>
  </svg>

  <script>
    let curStep = 0;
    const btns = [document.getElementById('btn0'), document.getElementById('btn1'), document.getElementById('btn2')];
    const glycH = document.getElementById('glycH');
    const faOH1 = document.getElementById('faOH1');
    const faOH2 = document.getElementById('faOH2');
    const faOH3 = document.getElementById('faOH3');
    const waterLeaves = document.getElementById('waterLeaves');
    const esterBonds = document.getElementById('esterBonds');

    function setStep(s) {
      curStep = s;
      btns.forEach((b, i) => b.classList.toggle('active', i === s));

      if (s === 0) {
        // Reactants
        glycH.setAttribute('class', 'visible');
        faOH1.setAttribute('class', 'visible');
        faOH2.setAttribute('class', 'visible');
        faOH3.setAttribute('class', 'visible');
        waterLeaves.setAttribute('class', 'hidden');
        esterBonds.setAttribute('class', 'hidden');
      } else if (s === 1) {
        // Condensation
        glycH.setAttribute('class', 'visible');
        faOH1.setAttribute('class', 'visible');
        faOH2.setAttribute('class', 'visible');
        faOH3.setAttribute('class', 'visible');
        waterLeaves.setAttribute('class', 'visible');
        esterBonds.setAttribute('class', 'hidden');
      } else if (s === 2) {
        // Ester bonds formed
        glycH.setAttribute('class', 'hidden');
        faOH1.setAttribute('class', 'hidden');
        faOH2.setAttribute('class', 'hidden');
        faOH3.setAttribute('class', 'hidden');
        waterLeaves.setAttribute('class', 'hidden');
        esterBonds.setAttribute('class', 'visible');
      }
    }

    // Auto cycle calmly
    let timer = setInterval(() => {
      setStep((curStep + 1) % 3);
    }, 4000);

    // Stop auto cycle on user interaction
    btns.forEach(btn => {
      btn.addEventListener('click', () => clearInterval(timer));
    });
  </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: #f8fafc;
      min-height: 100vh;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      padding: 16px;
      user-select: none;
    }

    .controls {
      display: inline-flex;
      gap: 4px;
      margin-bottom: 20px;
      background: #e2e8f0;
      padding: 4px;
      border-radius: 999px;
      max-width: 100%;
    }

    .btn-toggle {
      border: none;
      background: transparent;
      padding: 8px 14px;
      font-size: 13px;
      font-weight: 700;
      color: #1e293b; /* High contrast against #e2e8f0 (> 4.5:1) */
      border-radius: 999px;
      cursor: pointer;
      transition: background 0.2s ease, color 0.2s ease, box-shadow 0.2s ease;
      white-space: nowrap;
    }

    .btn-toggle.active {
      background: #ffffff;
      color: #0f172a;
      box-shadow: 0 2px 6px rgba(0, 0, 0, 0.1);
    }

    .stage {
      width: 100%;
      max-width: 580px;
      display: flex;
      flex-direction: column;
      gap: 16px;
    }

    .diagram-row {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 12px;
      width: 100%;
    }

    .panel {
      flex: 1;
      width: 100%;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      padding: 16px 12px;
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      box-shadow: 0 2px 8px rgba(30, 41, 69, 0.05);
      min-height: 130px;
    }

    .label-title {
      font-size: 15px;
      font-weight: 700;
      color: #1e2945;
      text-align: center;
      margin-bottom: 2px;
    }

    .label-sub {
      font-size: 12px;
      font-weight: 600;
      color: #64748b;
      text-align: center;
      margin-bottom: 12px;
    }

    .monomer-container {
      display: flex;
      gap: 8px;
      align-items: center;
      justify-content: center;
      height: 44px;
    }

    .polymer-container {
      display: flex;
      align-items: center;
      justify-content: center;
      height: 44px;
      flex-wrap: nowrap;
    }

    .unit {
      width: 34px;
      height: 34px;
      border-radius: 50%;
      background: linear-gradient(135deg, #22b7ff 0%, #0091db 100%);
      border: 2px solid #ffffff;
      box-shadow: 0 2px 6px rgba(0, 145, 219, 0.35);
      display: flex;
      align-items: center;
      justify-content: center;
      color: #ffffff;
      font-size: 11px;
      font-weight: 700;
      flex-shrink: 0;
    }

    .bond {
      width: 8px;
      height: 4px;
      background: #1e2945;
      border-radius: 2px;
      flex-shrink: 0;
    }

    .arrow-container {
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      width: 68px;
      flex-shrink: 0;
      text-align: center;
    }

    .arrow-badge {
      font-size: 11px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.5px;
      padding: 3px 8px;
      border-radius: 6px;
      background: #e0f2fe;
      color: #0369a1;
      margin-bottom: 4px;
      white-space: nowrap;
      transition: background 0.2s ease, color 0.2s ease;
    }

    .arrow-icon {
      font-size: 24px;
      color: #0284c7;
      line-height: 1;
      transition: transform 0.3s ease;
      display: inline-block;
    }

    .reversed .arrow-icon {
      transform: rotate(180deg);
    }

    /* Responsive adjustments for narrow screens (350px mobile) */
    @media (max-width: 480px) {
      .diagram-row {
        flex-direction: column;
        gap: 8px;
      }

      .arrow-container {
        width: 100%;
        padding: 4px 0;
      }

      .arrow-icon {
        transform: rotate(90deg);
      }

      .reversed .arrow-icon {
        transform: rotate(-90deg);
      }

      .btn-toggle {
        padding: 7px 10px;
        font-size: 12px;
      }
    }
  </style>
</head>
<body>

  <div class="controls">
    <button id="btnSynthesis" class="btn-toggle active">Synthesis (Build)</button>
    <button id="btnBreakdown" class="btn-toggle">Digestion (Break)</button>
  </div>

  <div class="stage">
    <div class="diagram-row" id="diagramRow">
      
      <div class="panel">
        <div class="label-title">Monomer</div>
        <div class="label-sub">Single Unit</div>
        <div class="monomer-container">
          <div class="unit">1</div>
        </div>
      </div>

      
      <div class="arrow-container" id="arrowBox">
        <div class="arrow-badge" id="arrowLabel">Build</div>
        <div class="arrow-icon">➔</div>
      </div>

      
      <div class="panel">
        <div class="label-title">Polymer</div>
        <div class="label-sub">Long Chain</div>
        <div class="polymer-container">
          <div class="unit">1</div>
          <div class="bond"></div>
          <div class="unit">2</div>
          <div class="bond"></div>
          <div class="unit">3</div>
          <div class="bond"></div>
          <div class="unit">4</div>
        </div>
      </div>
    </div>
  </div>

  <script>
    const btnSynthesis = document.getElementById('btnSynthesis');
    const btnBreakdown = document.getElementById('btnBreakdown');
    const arrowBox = document.getElementById('arrowBox');
    const arrowLabel = document.getElementById('arrowLabel');

    function setMode(mode) {
      if (mode === 'synthesis') {
        btnSynthesis.classList.add('active');
        btnBreakdown.classList.remove('active');
        arrowBox.classList.remove('reversed');
        arrowLabel.textContent = 'Build';
        arrowLabel.style.background = '#e0f2fe';
        arrowLabel.style.color = '#0369a1';
      } else {
        btnBreakdown.classList.add('active');
        btnSynthesis.classList.remove('active');
        arrowBox.classList.add('reversed');
        arrowLabel.textContent = 'Break';
        arrowLabel.style.background = '#fee2e2';
        arrowLabel.style.color = '#b91c1c';
      }
    }

    btnSynthesis.addEventListener('click', () => setMode('synthesis'));
    btnBreakdown.addEventListener('click', () => setMode('breakdown'));
  </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;
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    }

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

    /* Central Hub */
    .hub {
      background: #e0f2fe;
      border: 2px solid #38bdf8;
      border-radius: 24px;
      padding: 8px 16px;
      display: flex;
      align-items: center;
      gap: 8px;
      font-weight: 700;
      font-size: 14px;
      color: #0369a1;
      box-shadow: 0 2px 6px rgba(56, 189, 248, 0.2);
    }

    .hub-energy {
      display: inline-flex;
      align-items: center;
      gap: 4px;
      background: #fef08a;
      color: #854d0e;
      padding: 2px 8px;
      border-radius: 12px;
      font-size: 12px;
      font-weight: 800;
    }

    /* 3 Main Branches Grid */
    .branches-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 10px;
      width: 100%;
      max-width: 640px;
    }

    @media (max-width: 520px) {
      .branches-grid {
        grid-template-columns: 1fr;
        gap: 8px;
      }
    }

    /* Card Styling */
    .branch-card {
      background: #f8fafc;
      border: 2px solid #e2e8f0;
      border-radius: 16px;
      padding: 12px;
      cursor: pointer;
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      gap: 8px;
      transition: border-color 0.25s ease, background-color 0.25s ease, box-shadow 0.25s ease;
      user-select: none;
      position: relative;
    }

    .branch-card:hover {
      background: #ffffff;
      border-color: #94a3b8;
    }

    .branch-card.active {
      background: #ffffff;
      border-color: #2563eb;
      box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
    }

    .card-title {
      font-size: 13px;
      font-weight: 700;
      color: #1e2945;
      display: flex;
      align-items: center;
      gap: 4px;
    }

    .card-tag {
      font-size: 11px;
      font-weight: 600;
      color: #64748b;
      background: #edf2f7;
      padding: 2px 6px;
      border-radius: 6px;
    }

    /* Visual Box */
    .visual-box {
      width: 100%;
      height: 90px;
      background: #f1f5f9;
      border-radius: 10px;
      display: flex;
      align-items: center;
      justify-content: center;
      position: relative;
      overflow: hidden;
    }

    /* Visual 1: Synthesis */
    .synthesis-wrap {
      display: flex;
      align-items: center;
      gap: 6px;
      font-size: 11px;
      font-weight: 700;
    }

    .monomer {
      width: 14px;
      height: 14px;
      border-radius: 50%;
      background: #a855f7;
      display: inline-block;
      box-shadow: 0 1px 3px rgba(0,0,0,0.15);
      animation: pulseDot 2s ease-in-out infinite alternate;
    }

    .polymer {
      display: flex;
      align-items: center;
      background: #f3e8ff;
      border: 1px dashed #a855f7;
      padding: 4px 6px;
      border-radius: 8px;
      gap: 3px;
    }

    .polymer .monomer {
      width: 12px;
      height: 12px;
      animation: none;
    }

    /* Visual 2: Active Transport */
    .membrane-wrap {
      width: 100%;
      height: 100%;
      display: flex;
      flex-direction: column;
      justify-content: space-between;
      padding: 6px 8px;
      position: relative;
    }

    .membrane-bar {
      position: absolute;
      top: 50%;
      left: 0;
      right: 0;
      height: 12px;
      background: #cbd5e1;
      transform: translateY(-50%);
      display: flex;
      align-items: center;
      justify-content: center;
      z-index: 1;
    }

    .pump-gate {
      width: 28px;
      height: 20px;
      background: #10b981;
      border-radius: 4px;
      color: #fff;
      font-size: 9px;
      font-weight: 800;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .ion-zone {
      display: flex;
      justify-content: space-around;
      align-items: center;
      height: 30px;
      z-index: 2;
    }

    .ion {
      width: 11px;
      height: 11px;
      background: #059669;
      color: #fff;
      border-radius: 50%;
      font-size: 8px;
      font-weight: 800;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .pump-arrow {
      position: absolute;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
      color: #047857;
      font-weight: 900;
      font-size: 13px;
      z-index: 3;
      animation: pumpMove 1.8s ease-in-out infinite;
    }

    /* Visual 3: Movement & Heat */
    .muscle-wrap {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 6px;
      width: 100%;
    }

    .fibers-bar {
      width: 70%;
      height: 14px;
      background: #fca5a5;
      border: 1px solid #ef4444;
      border-radius: 4px;
      position: relative;
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 0 4px;
      animation: contractBar 2.2s ease-in-out infinite alternate;
    }

    .temp-badge {
      background: #fee2e2;
      border: 1px solid #f87171;
      color: #991b1b;
      padding: 2px 8px;
      border-radius: 12px;
      font-size: 11px;
      font-weight: 700;
      display: flex;
      align-items: center;
      gap: 3px;
    }

    /* Detail Banner */
    .detail-view {
      width: 100%;
      max-width: 640px;
      background: #ffffff;
      border: 1.5px solid #cbd5e1;
      border-radius: 12px;
      padding: 10px 14px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 12px;
      font-size: 13px;
      color: #1e2945;
    }

    .detail-text {
      font-weight: 600;
    }

    .detail-summary {
      font-size: 12px;
      color: #475569;
      font-weight: 500;
    }

    @keyframes pulseDot {
      0% { transform: scale(0.9); opacity: 0.7; }
      100% { transform: scale(1.1); opacity: 1; }
    }

    @keyframes pumpMove {
      0% { transform: translate(-50%, 8px); opacity: 0.3; }
      50% { opacity: 1; }
      100% { transform: translate(-50%, -12px); opacity: 0.3; }
    }

    @keyframes contractBar {
      0% { width: 85%; }
      100% { width: 55%; }
    }
  </style>
</head>
<body>

  
  <div class="hub">
    <span>Respiration</span>
    <span class="hub-energy">⚡ ATP Energy</span>
  </div>

  
  <div class="branches-grid">
    
    
    <div class="branch-card active" id="card-0" onclick="selectBranch(0)">
      <div class="card-title">1. Synthesis</div>
      <div class="visual-box">
        <div class="synthesis-wrap">
          <div style="display:flex; gap:3px;">
            <span class="monomer"></span>
            <span class="monomer"></span>
          </div>
          <span style="color:#a855f7;">+ ⚡ →</span>
          <div class="polymer">
            <span class="monomer"></span>
            <span class="monomer"></span>
            <span class="monomer"></span>
          </div>
        </div>
      </div>
      <div class="card-tag">Monomers → Polymers</div>
    </div>

    
    <div class="branch-card" id="card-1" onclick="selectBranch(1)">
      <div class="card-title">2. Active Transport</div>
      <div class="visual-box">
        <div class="membrane-wrap">
          <div class="ion-zone" style="justify-content: flex-end; gap: 4px;">
            <span style="font-size:9px; color:#065f46; font-weight:700;">High [ ]</span>
            <span class="ion">+</span><span class="ion">+</span><span class="ion">+</span>
          </div>
          <div class="membrane-bar">
            <div class="pump-gate">Pump</div>
          </div>
          <div class="pump-arrow">▲</div>
          <div class="ion-zone" style="justify-content: flex-start; gap: 4px;">
            <span class="ion">+</span>
            <span style="font-size:9px; color:#065f46; font-weight:700;">Low [ ]</span>
          </div>
        </div>
      </div>
      <div class="card-tag">Against Gradient</div>
    </div>

    
    <div class="branch-card" id="card-2" onclick="selectBranch(2)">
      <div class="card-title">3. Muscle & Heat</div>
      <div class="visual-box">
        <div class="muscle-wrap">
          <div class="fibers-bar">
            <span style="font-size:9px; color:#b91c1c;">◀</span>
            <span style="font-size:9px; font-weight:700; color:#991b1b;">Muscle</span>
            <span style="font-size:9px; color:#b91c1c;">▶</span>
          </div>
          <div class="temp-badge">
            <span>🌡️</span> 37°C Constant
          </div>
        </div>
      </div>
      <div class="card-tag">Contraction + Warmth</div>
    </div>

  </div>

  
  <div class="detail-view">
    <span class="detail-text" id="detail-title">Synthesis / Building:</span>
    <span class="detail-summary" id="detail-desc">Combining glucose into glycogen/starch & amino acids into proteins.</span>
  </div>

  <script>
    const details = [
      {
        title: "Synthesis / Building Reactions:",
        desc: "Combines small molecules into larger ones (e.g. glucose → glycogen, amino acids → proteins)."
      },
      {
        title: "Active Transport Across Membranes:",
        desc: "Powers protein pumps to move mineral ions against their concentration gradient."
      },
      {
        title: "Movement & Thermoregulation:",
        desc: "Contracts muscle fibers for movement and releases thermal energy to maintain ~37°C."
      }
    ];

    function selectBranch(index) {
      for (let i = 0; i < 3; i++) {
        const card = document.getElementById('card-' + i);
        if (i === index) {
          card.classList.add('active');
        } else {
          card.classList.remove('active');
        }
      }
      document.getElementById('detail-title').textContent = details[index].title;
      document.getElementById('detail-desc').textContent = details[index].desc;
    }
  </script>
</body>
</html>

Cellular Respiration: An Exothermic Continuous Process

<!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: transparent;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-start;
      padding: 10px 8px;
      user-select: none;
      -webkit-user-select: none;
    }

    .toolbar {
      display: flex;
      flex-wrap: wrap;
      gap: 6px;
      justify-content: center;
      margin-bottom: 8px;
      width: 100%;
      max-width: 580px;
    }

    .btn-tab {
      background: #ffffff;
      border: 1px solid #d1d5db;
      color: #1e2945;
      font-size: 13px;
      font-weight: 600;
      padding: 6px 12px;
      border-radius: 20px;
      cursor: pointer;
      box-shadow: 0 1px 2px rgba(0,0,0,0.05);
      transition: all 0.25s ease;
      display: inline-flex;
      align-items: center;
      gap: 5px;
    }

    .btn-tab:hover {
      background: #f3f4f6;
    }

    .btn-tab.active {
      background: #1e2945;
      color: #ffffff;
      border-color: #1e2945;
      box-shadow: 0 2px 5px rgba(30,41,69,0.25);
    }

    .diagram-svg-container {
      width: 100%;
      max-width: 580px;
      height: auto;
      position: relative;
    }

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

    /* SVG Elements Styling */
    .axis { stroke: #64748b; stroke-width: 2; stroke-linecap: round; }
    .axis-arrow { fill: #64748b; }
    .grid-line { stroke: #e2e8f0; stroke-width: 1.5; stroke-dasharray: 4 4; }

    .curve-bg {
      stroke: #cbd5e1;
      stroke-width: 5;
      fill: none;
      stroke-linecap: round;
    }

    .curve-segment {
      fill: none;
      stroke-linecap: round;
      transition: stroke-width 0.3s ease, opacity 0.3s ease, stroke 0.3s ease;
    }

    .segment-breaking { stroke: #3b82f6; stroke-width: 5; }
    .segment-forming { stroke: #f97316; stroke-width: 5; }

    .highlighted {
      stroke-width: 9 !important;
      filter: drop-shadow(0 0 6px rgba(0,0,0,0.15));
    }

    .dimmed {
      opacity: 0.25 !important;
    }

    .label-badge {
      transition: opacity 0.3s ease, transform 0.3s ease;
    }

    .energy-arrow {
      stroke-dasharray: 6 3;
      animation: energyFlow 1.2s linear infinite;
    }

    @keyframes energyFlow {
      to { stroke-dashoffset: -18; }
    }
  </style>
</head>
<body>

  
  <div class="toolbar">
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    <button class="btn-tab" data-mode="break" onclick="setMode('break')">1. Bond Breaking (+Eₐ)</button>
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UK-GCSE-SCIENCE-BIO-CB-03

Child standards (4)

Aligned learning resources

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