<!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;
      background: #ffffff;
      color: #1e293b;
      width: 100%;
      padding: 8px 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-start;
      gap: 8px;
    }

    /* Tabs */
    .tabs {
      display: flex;
      gap: 6px;
      background: #f1f5f9;
      padding: 4px;
      border-radius: 20px;
    }
    .tab-btn {
      border: none;
      background: transparent;
      padding: 6px 14px;
      border-radius: 16px;
      font-size: 14px;
      font-weight: 600;
      color: #64748b;
      cursor: pointer;
      transition: background-color 0.2s ease, color 0.2s ease, box-shadow 0.2s ease;
    }
    .tab-btn.active {
      background: #2563eb;
      color: #ffffff;
      box-shadow: 0 2px 5px rgba(37, 99, 235, 0.25);
    }
    .tab-btn:focus-visible {
      outline: 2px solid #2563eb;
      outline-offset: 1px;
    }

    /* Views */
    .view-container {
      position: relative;
      width: 100%;
      max-width: 540px;
      aspect-ratio: 540 / 300;
    }
    .view-panel {
      position: absolute;
      inset: 0;
      width: 100%;
      height: 100%;
      opacity: 0;
      pointer-events: none;
      transition: opacity 0.25s ease-in-out;
    }
    .view-panel.active {
      opacity: 1;
      pointer-events: auto;
    }

    /* SVG Styling */
    svg {
      width: 100%;
      height: 100%;
      display: block;
    }

    .label-title {
      font-size: 15px;
      font-weight: 700;
      fill: #0f172a;
    }
    .label-val-atom {
      font-size: 14px;
      font-weight: 700;
      fill: #1d4ed8;
    }
    .label-val-nuc {
      font-size: 14px;
      font-weight: 700;
      fill: #dc2626;
    }
    .label-sub {
      font-size: 13px;
      font-weight: 600;
      fill: #475569;
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    /* Scale Difference Badge */
    .ratio-badge {
      display: flex;
      flex-wrap: wrap;
      align-items: center;
      justify-content: center;
      gap: 6px;
      background: #eff6ff;
      border: 1px solid #bfdbfe;
      padding: 6px 14px;
      border-radius: 12px;
      font-size: 13.5px;
      font-weight: 600;
      color: #1e40af;
      text-align: center;
      max-width: 540px;
      width: 100%;
    }
    .ratio-badge strong {
      color: #1d4ed8;
      font-weight: 800;
    }

    @media (max-width: 400px) {
      .tab-btn {
        font-size: 13px;
        padding: 5px 10px;
      }
      .ratio-badge {
        font-size: 12.5px;
        padding: 6px 10px;
      }
    }
  </style>
</head>
<body>

  
  <div class="tabs" role="tablist" aria-label="Diagram Views">
    <button class="tab-btn active" id="tabAtom" role="tab" aria-selected="true" onclick="showView('atom')">🔬 Atomic Scale</button>
    <button class="tab-btn" id="tabStadium" role="tab" aria-selected="false" onclick="showView('stadium')">🏟️ Stadium Analogy</button>
  </div>

  
  <div class="view-container">

    
    <div class="view-panel active" id="panelAtom" role="tabpanel">
      <svg viewBox="0 0 540 300" aria-label="Atom versus Nucleus Scale Diagram">
        <defs>
          
          <radialGradient id="cloudGrad" cx="50%" cy="50%" r="50%">
            <stop offset="0%" stop-color="#93c5fd" stop-opacity="0.6"/>
            <stop offset="65%" stop-color="#bfdbfe" stop-opacity="0.35"/>
            <stop offset="100%" stop-color="#dbeafe" stop-opacity="0.08"/>
          </radialGradient>
          
          <radialGradient id="protGrad" cx="35%" cy="35%" r="65%">
            <stop offset="0%" stop-color="#f87171"/>
            <stop offset="100%" stop-color="#dc2626"/>
          </radialGradient>
          <radialGradient id="neutGrad" cx="35%" cy="35%" r="65%">
            <stop offset="0%" stop-color="#cbd5e1"/>
            <stop offset="100%" stop-color="#64748b"/>
          </radialGradient>
        </defs>

        
        <circle cx="150" cy="170" r="105" fill="url(#cloudGrad)" stroke="#3b82f6" stroke-width="1.75" stroke-dasharray="5 4"/>

        
        <line x1="150" y1="170" x2="255" y2="170" stroke="#2563eb" stroke-width="1.75"/>
        <circle cx="150" cy="170" r="3.5" fill="#2563eb"/>
        <circle cx="255" cy="170" r="3.5" fill="#2563eb"/>
        <text x="202" y="163" text-anchor="middle" font-size="12" font-weight="700" fill="#2563eb">Radius</text>

        
        <rect x="30" y="8" width="240" height="42" rx="8" fill="#f8fafc" stroke="#cbd5e1" stroke-width="1"/>
        <text x="150" y="25" text-anchor="middle" class="label-title">Atom Radius</text>
        <text x="150" y="42" text-anchor="middle" class="label-val-atom">≈ 1 × 10⁻¹⁰ m (0.1 nm)</text>

        
        <circle cx="150" cy="170" r="3" fill="#dc2626"/>

        
        <polygon points="150,170 348,92 348,228" fill="#fee2e2" opacity="0.45"/>
        <line x1="150" y1="170" x2="348" y2="92" stroke="#ef4444" stroke-width="1.5" stroke-dasharray="3 3"/>
        <line x1="150" y1="170" x2="348" y2="228" stroke="#ef4444" stroke-width="1.5" stroke-dasharray="3 3"/>

        
        <circle cx="425" cy="160" r="68" fill="#ffffff" stroke="#ef4444" stroke-width="2.5"/>

        
        <circle cx="410" cy="144" r="14" fill="url(#protGrad)"/>
        <text x="410" y="148" text-anchor="middle" font-size="11" font-weight="800" fill="#ffffff">+</text>

        <circle cx="440" cy="146" r="14" fill="url(#neutGrad)"/>
        
        <circle cx="424" cy="172" r="14" fill="url(#protGrad)"/>
        <text x="424" y="176" text-anchor="middle" font-size="11" font-weight="800" fill="#ffffff">+</text>

        <circle cx="406" cy="168" r="14" fill="url(#neutGrad)"/>
        <circle cx="442" cy="174" r="14" fill="url(#neutGrad)"/>
        
        <circle cx="426" cy="152" r="14" fill="url(#protGrad)"/>
        <text x="426" y="156" text-anchor="middle" font-size="11" font-weight="800" fill="#ffffff">+</text>

        
        <rect x="330" y="8" width="190" height="42" rx="8" fill="#fef2f2" stroke="#fecaca" stroke-width="1"/>
        <text x="425" y="25" text-anchor="middle" class="label-title">Nucleus Radius</text>
        <text x="425" y="42" text-anchor="middle" class="label-val-nuc">≈ 1 × 10⁻¹⁴ m</text>

        
        <text x="425" y="248" text-anchor="middle" class="label-sub">Magnified Core</text>
        <text x="425" y="265" text-anchor="middle" font-size="12" font-weight="600" fill="#64748b">(Protons + Neutrons)</text>
      </svg>
    </div>

    
    <div class="view-panel" id="panelStadium" role="tabpanel">
      <svg viewBox="0 0 540 300" aria-label="Stadium Analogy Diagram">
        
        <rect x="35" y="42" width="470" height="195" rx="97.5" fill="#e2e8f0" stroke="#94a3b8" stroke-width="2"/>
        
        <rect x="95" y="70" width="350" height="139" rx="69.5" fill="#22c55e" stroke="#16a34a" stroke-width="2"/>

        
        <line x1="270" y1="70" x2="270" y2="209" stroke="#ffffff" stroke-width="2" opacity="0.85"/>
        <circle cx="270" cy="139.5" r="32" fill="none" stroke="#ffffff" stroke-width="2" opacity="0.85"/>

        
        <rect x="175" y="8" width="190" height="28" rx="14" fill="#0f172a" stroke="none"/>
        <text x="270" y="27" text-anchor="middle" fill="#ffffff" font-size="14" font-weight="700">Stadium = Atom</text>

        
        <circle cx="270" cy="139.5" r="4" fill="#3b82f6" stroke="#ffffff" stroke-width="1.5"/>
        <circle cx="270" cy="139.5" r="10" fill="none" stroke="#3b82f6" stroke-width="1.5" stroke-dasharray="2 2"/>

        
        <path d="M 270 139.5 L 340 92 L 405 92" fill="none" stroke="#0f172a" stroke-width="1.75"/>
        <rect x="405" y="72" width="125" height="42" rx="6" fill="#f8fafc" stroke="#94a3b8" stroke-width="1"/>
        <text x="467" y="90" text-anchor="middle" font-size="13" font-weight="700" fill="#dc2626">Marble = Nucleus</text>
        <text x="467" y="106" text-anchor="middle" font-size="11.5" font-weight="600" fill="#64748b">at center spot</text>

        
        <rect x="70" y="252" width="400" height="34" rx="17" fill="#f8fafc" stroke="#cbd5e1" stroke-width="1"/>
        <text x="270" y="274" text-anchor="middle" font-size="13.5" font-weight="600" fill="#334155">
          If an atom is a massive stadium, its nucleus is a marble at the center.
        </text>
      </svg>
    </div>

  </div>

  
  <div class="ratio-badge">
    <span>Scale Comparison:</span>
    <strong>Atom is ~10,000× larger than its nucleus (10⁴)</strong>
  </div>

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      const tabStadium = document.getElementById('tabStadium');
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        panelStadium.classList.add('active');
        panelAtom.classList.remove('active');
      }
    }
  </script>
</body>
</html>

Typical Dimensions and Order of Magnitude of Atoms and Molecules

<!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>
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      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      color: #1e293b;
      background: #f8fafc;
      width: 100%;
      padding: 16px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
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    /* Controls Header */
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      display: flex;
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      gap: 8px;
      width: 100%;
      max-width: 480px;
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      font-size: 14px;
      font-weight: 600;
      color: #64748b;
      cursor: pointer;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 4px;
      transition: all 0.25s ease;
    }

    .step-btn.active {
      background: #0284c7;
      border-color: #0284c7;
      color: #ffffff;
      box-shadow: 0 2px 6px rgba(2, 132, 199, 0.25);
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    .play-btn {
      width: 38px;
      height: 38px;
      border: 1px solid #cbd5e1;
      background: #ffffff;
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      font-size: 14px;
      color: #334155;
      cursor: pointer;
      display: flex;
      align-items: center;
      justify-content: center;
    }

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      flex-direction: column;
      gap: 10px;
      flex: 1;
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      border: 1.5px solid #e2e8f0;
      border-radius: 12px;
      padding: 12px 16px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      transition: all 0.3s ease;
      opacity: 0.45;
      position: relative;
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    .step-card.active {
      opacity: 1;
      border-color: #0284c7;
      box-shadow: 0 4px 12px rgba(2, 132, 199, 0.12);
      background: #ffffff;
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    .step-num {
      width: 24px;
      height: 24px;
      border-radius: 50%;
      background: #f1f5f9;
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      display: flex;
      align-items: center;
      justify-content: center;
      margin-right: 12px;
      flex-shrink: 0;
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    .step-card.active .step-num {
      background: #0284c7;
      color: #ffffff;
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    .step-content {
      flex: 1;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 12px;
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    /* Math Elements */
    .math {
      font-family: 'Cambria Math', 'Times New Roman', serif;
      font-size: 20px;
      display: inline-flex;
      align-items: center;
      color: #0f172a;
    }

    .fraction {
      display: inline-flex;
      flex-direction: column;
      align-items: center;
      vertical-align: middle;
      padding: 0 4px;
    }

    .numerator {
      border-bottom: 1.5px solid #0f172a;
      padding-bottom: 2px;
      width: 100%;
      text-align: center;
    }

    .denominator {
      padding-top: 2px;
      width: 100%;
      text-align: center;
    }

    .exp-blue {
      color: #0284c7;
      font-weight: 700;
    }

    .exp-purple {
      color: #7c3aed;
      font-weight: 700;
    }

    .exp-green {
      color: #059669;
      font-weight: 700;
    }

    .badge {
      font-size: 11px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.5px;
      padding: 3px 8px;
      border-radius: 6px;
      background: #f1f5f9;
      color: #475569;
      white-space: nowrap;
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    .step-card.active .badge {
      background: #e0f2fe;
      color: #0369a1;
    }

    /* Step Specific Styles */
    .subtraction-detail {
      font-size: 14px;
      font-family: system-ui, sans-serif;
      display: flex;
      align-items: center;
      gap: 4px;
      background: #f8fafc;
      padding: 4px 8px;
      border-radius: 6px;
      border: 1px dashed #cbd5e1;
    }

    .highlight-box {
      font-weight: 700;
      color: #059669;
    }
  </style>
</head>
<body>

  
  <div class="controls">
    <button class="step-btn active" id="btn0" onclick="goToStep(0)">1. Ratio</button>
    <button class="step-btn" id="btn1" onclick="goToStep(1)">2. Index Law</button>
    <button class="step-btn" id="btn2" onclick="goToStep(2)">3. Scale</button>
    <button class="play-btn" id="playBtn" onclick="togglePlay()" aria-label="Play/Pause">⏸</button>
  </div>

  
  <div class="calc-flow">

    
    <div class="step-card active" id="card0" onclick="goToStep(0)">
      <div class="step-num">1</div>
      <div class="step-content">
        <div class="math">
          <div class="fraction">
            <span class="numerator">10<sup class="exp-blue">-10</sup> m</span>
            <span class="denominator">10<sup class="exp-purple">-14</sup> m</span>
          </div>
        </div>
        <span class="badge">Atom ÷ Nucleus</span>
      </div>
    </div>

    
    <div class="step-card" id="card1" onclick="goToStep(1)">
      <div class="step-num">2</div>
      <div class="step-content">
        <div class="math">
          10<sup class="exp-blue">-10</sup><sup style="margin:0 1px;">-</sup><sup class="exp-purple">(-14)</sup>
          <span style="margin: 0 6px; font-size: 16px;">=</span>
          10<sup class="exp-green">+4</sup>
        </div>
        <div class="subtraction-detail">
          <span>-10 + 14 =</span>
          <span class="highlight-box">+4</span>
        </div>
      </div>
    </div>

    
    <div class="step-card" id="card2" onclick="goToStep(2)">
      <div class="step-num">3</div>
      <div class="step-content">
        <div class="math">
          10<sup class="exp-green">4</sup>
          <span style="margin: 0 6px; font-size: 16px;">=</span>
          <strong style="color:#059669;">10,000×</strong>
        </div>
        <span class="badge" style="background:#d1fae5; color:#065f46;">4 Orders of Mag.</span>
      </div>
    </div>

  </div>

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    startTimer();
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</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, sans-serif;
    }

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

    /* Track & Scale Ruler */
    .scale-container {
      width: 100%;
      max-width: 580px;
      margin-top: 4px;
    }

    .ruler-track {
      position: relative;
      height: 6px;
      background: #e2e8f0;
      border-radius: 999px;
      margin: 28px 12px 20px;
    }

    .ruler-fill {
      position: absolute;
      left: 0;
      top: 0;
      height: 100%;
      background: #22b7ff;
      border-radius: 999px;
      transition: width 0.4s ease;
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      position: relative;
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      height: 0;
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      position: absolute;
      top: -11px;
      transform: translateX(-50%);
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      border-radius: 50%;
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      border: 2px solid #cbd5e1;
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      font-size: 11px;
      font-weight: 700;
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      transition: all 0.3s ease;
      padding: 0;
      outline: none;
    }

    .marker-btn.active {
      border-color: #22b7ff;
      background: #22b7ff;
      color: #fff;
      box-shadow: 0 0 0 4px rgba(34, 183, 255, 0.25);
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      position: absolute;
      top: 24px;
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      font-weight: 600;
      color: #64748b;
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      border: 1px solid #e2e8f0;
      border-radius: 16px;
      padding: 16px 20px;
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      gap: 10px;
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      justify-content: center;
      font-size: 36px;
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      font-weight: 700;
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      align-items: center;
      gap: 12px;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
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      font-size: 14px;
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<body>

  <div class="scale-container">
    <div class="ruler-track">
      <div class="ruler-fill" id="fill"></div>
      <div class="markers" id="markerContainer"></div>
    </div>
  </div>

  <div class="stage-card">
    <div class="visual-avatar" id="avatar">✋</div>
    <div class="item-name" id="name">Hand</div>
    <div class="measurements">
      <span class="val-meters" id="meters">10<sup>-1</sup> m</span>
      <span class="val-divider">•</span>
      <span class="val-unit" id="unit">10 cm</span>
    </div>
  </div>

  <div class="controls">
    <button class="ctrl-btn" id="prevBtn" aria-label="Previous">←</button>
    <button class="ctrl-btn primary" id="playBtn">⏸</button>
    <button class="ctrl-btn" id="nextBtn" aria-label="Next">→</button>
  </div>

  <script>
    const data = [
      { name: "Hand", icon: "✋", m: "10<sup>-1</sup> m", unit: "10 cm", pos: 0 },
      { name: "Cell", icon: "🦠", m: "10<sup>-5</sup> m", unit: "10 μm", pos: 25 },
      { name: "Glucose", icon: "🧪", m: "10<sup>-9</sup> m", unit: "1 nm", pos: 50 },
      { name: "H Atom", icon: "⚛️", m: "10<sup>-10</sup> m", unit: "0.1 nm", pos: 75 },
      { name: "Nucleus", icon: "🎯", m: "10<sup>-14</sup> m", unit: "10 fm", pos: 100 }
    ];

    let current = 0;
    let playing = true;
    let timer = null;

    const fill = document.getElementById("fill");
    const avatar = document.getElementById("avatar");
    const nameEl = document.getElementById("name");
    const metersEl = document.getElementById("meters");
    const unitEl = document.getElementById("unit");
    const playBtn = document.getElementById("playBtn");
    const prevBtn = document.getElementById("prevBtn");
    const nextBtn = document.getElementById("nextBtn");
    const markerContainer = document.getElementById("markerContainer");

    // Build markers
    data.forEach((item, idx) => {
      const btn = document.createElement("button");
      btn.className = "marker-btn" + (idx === 0 ? " active" : "");
      btn.style.left = item.pos + "%";
      btn.textContent = idx + 1;
      btn.onclick = () => { goTo(idx); pause(); };

      const label = document.createElement("div");
      label.className = "marker-label" + (idx === 0 ? " active" : "");
      label.style.left = item.pos + "%";
      label.innerHTML = item.m;

      markerContainer.appendChild(btn);
      markerContainer.appendChild(label);
    });

    function update() {
      const item = data[current];
      fill.style.width = item.pos + "%";
      avatar.textContent = item.icon;
      nameEl.textContent = item.name;
      metersEl.innerHTML = item.m;
      unitEl.textContent = item.unit;

      const buttons = document.querySelectorAll(".marker-btn");
      const labels = document.querySelectorAll(".marker-label");

      buttons.forEach((b, i) => b.classList.toggle("active", i === current));
      labels.forEach((l, i) => l.classList.toggle("active", i === current));
    }

    function goTo(idx) {
      current = (idx + data.length) % data.length;
      update();
    }

    function play() {
      playing = true;
      playBtn.textContent = "⏸";
      clearInterval(timer);
      timer = setInterval(() => {
        current = (current + 1) % data.length;
        update();
      }, 3000);
    }

    function pause() {
      playing = false;
      playBtn.textContent = "▶";
      clearInterval(timer);
    }

    playBtn.onclick = () => {
      if (playing) pause();
      else play();
    };

    prevBtn.onclick = () => {
      pause();
      goTo(current - 1);
    };

    nextBtn.onclick = () => {
      pause();
      goTo(current + 1);
    };

    play();
  </script>
</body>
</html>

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

    /* Anatomy Header */
    .anatomy-row {
      display: flex;
      justify-content: center;
      align-items: center;
      gap: 8px;
      font-size: 28px;
      font-weight: 700;
    }
    .base-a {
      color: #2563eb;
      background: #eff6ff;
      border: 1px solid #bfdbfe;
      border-radius: 8px;
      padding: 2px 10px;
      display: inline-flex;
      flex-direction: column;
      align-items: center;
    }
    .power-n {
      color: #7c3aed;
      background: #f5f3ff;
      border: 1px solid #ddd6fe;
      border-radius: 8px;
      padding: 2px 10px;
      display: inline-flex;
      flex-direction: column;
      align-items: center;
    }
    .sub-tag {
      font-size: 11px;
      font-weight: 600;
      letter-spacing: 0.02em;
      margin-top: 2px;
    }

    /* Transformation Stage */
    .stage {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 12px 8px 8px 8px;
      display: flex;
      flex-direction: column;
      align-items: center;
      position: relative;
    }

    .digits-svg {
      width: 100%;
      max-width: 520px;
      height: 90px;
      overflow: visible;
    }

    .digit-text {
      font-size: 19px;
      font-family: monospace;
      font-weight: 700;
      fill: #475569;
      text-anchor: middle;
      dominant-baseline: middle;
    }
    .digit-target {
      fill: #2563eb;
    }
    .unit-text {
      font-size: 16px;
      font-weight: 600;
      fill: #64748b;
      dominant-baseline: middle;
    }

    .arc-path {
      fill: none;
      stroke: #cbd5e1;
      stroke-width: 1.5;
      stroke-dasharray: 2 2;
      transition: stroke 0.3s, stroke-width 0.3s;
    }
    .arc-path.active {
      stroke: #7c3aed;
      stroke-width: 2.5;
      stroke-dasharray: none;
    }

    .jump-num {
      font-size: 10px;
      font-weight: 700;
      fill: #94a3b8;
      text-anchor: middle;
    }
    .jump-num.active {
      fill: #7c3aed;
    }

    .decimal-dot {
      fill: #ef4444;
      transition: cx 0.25s ease, cy 0.25s ease;
    }

    /* Output Form */
    .output-row {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 12px;
      margin-top: 4px;
      font-size: 20px;
      font-weight: 700;
    }
    .badge {
      display: inline-flex;
      align-items: center;
      padding: 4px 10px;
      border-radius: 6px;
      font-size: 14px;
      font-weight: 600;
    }
    .badge-shift {
      background: #f5f3ff;
      color: #7c3aed;
      border: 1px solid #ddd6fe;
    }

    /* Controls */
    .controls {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
    }
    .btn {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 6px;
      padding: 5px 12px;
      font-size: 13px;
      font-weight: 600;
      color: #334155;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      transition: background 0.15s, border-color 0.15s;
    }
    .btn:active {
      background: #f1f5f9;
    }
    .btn-primary {
      background: #2563eb;
      color: #ffffff;
      border-color: #2563eb;
    }

    /* Conversion Bar */
    .conversion-bar {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 8px 12px;
      display: flex;
      align-items: center;
      justify-content: center;
      flex-wrap: wrap;
      gap: 8px;
      font-size: 14px;
      font-weight: 600;
      color: #334155;
      text-align: center;
    }
    .val-highlight {
      color: #0f172a;
      font-family: monospace;
      font-size: 15px;
    }
    .eq-sym {
      color: #94a3b8;
    }
  </style>
</head>
<body>

  
  <div class="anatomy-row">
    <div class="base-a">
      <span>A</span>
      <span class="sub-tag">1 ≤ A &lt; 10</span>
    </div>
    <span>×</span>
    <div class="power-n">
      <span>10<sup>n</sup></span>
      <span class="sub-tag">Power of 10</span>
    </div>
  </div>

  
  <div class="stage">
    <svg class="digits-svg" id="svgStage" viewBox="0 0 520 90">
      
      <g id="arcsGroup"></g>
      
      <g id="digitsGroup"></g>
      
      <circle id="movingDot" class="decimal-dot" cx="44" cy="56" r="4.5" />
    </svg>

    <div class="output-row">
      <span id="shiftBadge" class="badge badge-shift">→ 0 places</span>
      <span>=</span>
      <span style="font-family: monospace;">
        <span style="color:#2563eb;">1</span> × <span style="color:#7c3aed;" id="powerText">10<sup>0</sup></span> m
      </span>
    </div>
  </div>

  
  <div class="controls">
    <button class="btn" id="prevBtn" onclick="step(-1)">◀</button>
    <button class="btn btn-primary" id="playBtn" onclick="togglePlay()">⏸ Pause</button>
    <button class="btn" id="nextBtn" onclick="step(1)">▶</button>
    <button class="btn" onclick="resetSteps()">↺ Reset</button>
  </div>

  
  <div class="conversion-bar">
    <span class="val-highlight">0.1 nm</span>
    <span class="eq-sym">=</span>
    <span class="val-highlight">0.1 × 10<sup>-9</sup> m</span>
    <span class="eq-sym">=</span>
    <span class="val-highlight" style="color:#2563eb;">1 × <span style="color:#7c3aed;">10<sup>-10</sup></span> m</span>
  </div>

  <script>
    // Digits: 0 . 0 0 0 0 0 0 0 0 0 1
    // Total 11 numeric digits, 10 jump spaces
    const startX = 30;
    const spacing = 38;
    const baseY = 56;
    const totalJumps = 10;

    const digitsGroup = document.getElementById('digitsGroup');
    const arcsGroup = document.getElementById('arcsGroup');
    const movingDot = document.getElementById('movingDot');
    const shiftBadge = document.getElementById('shiftBadge');
    const powerText = document.getElementById('powerText');
    const playBtn = document.getElementById('playBtn');

    // Create Digits
    const digitChars = ['0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '1'];
    digitChars.forEach((ch, i) => {
      const x = startX + i * spacing;
      const text = document.createElementNS('http://www.w3.org/2000/svg', 'text');
      text.setAttribute('x', x);
      text.setAttribute('y', baseY);
      text.setAttribute('class', i === 10 ? 'digit-text digit-target' : 'digit-text');
      text.textContent = ch;
      digitsGroup.appendChild(text);
    });

    // Add Unit label 'm'
    const unit = document.createElementNS('http://www.w3.org/2000/svg', 'text');
    unit.setAttribute('x', startX + 10 * spacing + 28);
    unit.setAttribute('y', baseY);
    unit.setAttribute('class', 'unit-text');
    unit.textContent = 'm';
    digitsGroup.appendChild(unit);

    // Initial dot pos (between digit 0 and 1)
    const dotInitialX = startX + spacing * 0.38;
    const dotStepX = spacing;

    // Create Jump Arcs
    for (let i = 0; i < totalJumps; i++) {
      const x1 = dotInitialX + i * dotStepX;
      const x2 = x1 + dotStepX;
      const mx = (x1 + x2) / 2;
      const arcY = baseY - 24;

      const path = document.createElementNS('http://www.w3.org/2000/svg', 'path');
      path.setAttribute('id', `arc-${i}`);
      path.setAttribute('class', 'arc-path');
      path.setAttribute('d', `M ${x1} ${baseY - 2} Q ${mx} ${arcY} ${x2} ${baseY - 2}`);
      arcsGroup.appendChild(path);

      const num = document.createElementNS('http://www.w3.org/2000/svg', 'text');
      num.setAttribute('id', `num-${i}`);
      num.setAttribute('class', 'jump-num');
      num.setAttribute('x', mx);
      num.setAttribute('y', arcY - 4);
      num.textContent = (i + 1);
      arcsGroup.appendChild(num);
    }

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

    function render() {
      // Dot position
      const cx = dotInitialX + currentStep * dotStepX;
      movingDot.setAttribute('cx', cx);

      // Arcs & numbers highlighting
      for (let i = 0; i < totalJumps; i++) {
        const arc = document.getElementById(`arc-${i}`);
        const num = document.getElementById(`num-${i}`);
        if (i < currentStep) {
          arc.classList.add('active');
          num.classList.add('active');
        } else {
          arc.classList.remove('active');
          num.classList.remove('active');
        }
      }

      // Badges & text
      shiftBadge.textContent = `→ ${currentStep} place${currentStep === 1 ? '' : 's'}`;
      powerText.innerHTML = currentStep === 0 ? '10<sup>0</sup>' : `10<sup>-${currentStep}</sup>`;
    }

    function step(dir) {
      currentStep = (currentStep + dir + (totalJumps + 1)) % (totalJumps + 1);
      render();
    }

    function resetSteps() {
      currentStep = 0;
      render();
    }

    function tick() {
      if (!isPlaying) return;
      if (currentStep >= totalJumps) {
        currentStep = 0;
      } else {
        currentStep++;
      }
      render();
    }

    function togglePlay() {
      isPlaying = !isPlaying;
      playBtn.textContent = isPlaying ? '⏸ Pause' : '▶ Play';
      playBtn.classList.toggle('btn-primary', isPlaying);
    }

    timer = setInterval(tick, 900);
    render();
  </script>
</body>
</html>

UK-GCSE-SCIENCE-CHEM-AT-01-02

Aligned learning resources

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