<!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>Garden Bed Area Calculation</title>
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      color: #1e2945;
      background: transparent;
      padding: 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100%;
    }

    .stepper-nav {
      display: flex;
      gap: 6px;
      margin-bottom: 10px;
      width: 100%;
      max-width: 440px;
    }
    .step-btn {
      flex: 1;
      border: 1.5px solid #cbd5e1;
      background: #f8fafc;
      color: #334155;
      padding: 7px 4px;
      border-radius: 8px;
      font-size: 13px;
      font-weight: 700;
      cursor: pointer;
      text-align: center;
      transition: all 0.2s ease;
    }
    .step-btn:hover {
      background: #f1f5f9;
      border-color: #94a3b8;
    }
    .step-btn.active {
      background: #0284c7;
      color: #ffffff;
      border-color: #0284c7;
      box-shadow: 0 2px 5px rgba(2, 132, 199, 0.25);
    }

    .cards-container {
      width: 100%;
      max-width: 440px;
      display: flex;
      flex-direction: column;
      gap: 9px;
    }

    .math-card {
      background: #ffffff;
      border: 1.5px solid #cbd5e1;
      border-radius: 12px;
      padding: 11px 14px;
      transition: border-color 0.25s ease, box-shadow 0.25s ease, opacity 0.25s ease;
    }
    .math-card.active-card {
      border-color: #0284c7;
      box-shadow: 0 0 0 1px #0284c7, 0 3px 10px rgba(2, 132, 199, 0.12);
    }
    .math-card.dimmed {
      opacity: 0.72;
      border-color: #e2e8f0;
    }

    .card-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      margin-bottom: 8px;
    }
    .step-tag {
      font-size: 11px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.5px;
      color: #0369a1;
      background: #e0f2fe;
      padding: 3px 8px;
      border-radius: 6px;
    }
    .dimmed .step-tag {
      background: #f1f5f9;
      color: #475569;
    }
    .card-title {
      font-size: 13px;
      font-weight: 700;
      color: #1e2945;
    }

    /* Card 1 Garden Visual */
    .garden-visual-wrapper {
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      padding: 2px 0 4px 0;
    }
    .dim-top {
      margin-bottom: 4px;
      text-align: center;
      display: flex;
      align-items: center;
      gap: 6px;
    }
    .garden-main-row {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 10px;
      width: 100%;
    }
    .dim-left {
      text-align: right;
      display: flex;
      flex-direction: column;
      align-items: flex-end;
      min-width: 65px;
    }
    .dim-label {
      font-size: 13px;
      font-weight: 700;
      color: #0369a1;
      white-space: nowrap;
    }
    .dim-sub {
      font-size: 12px;
      font-weight: 600;
      color: #475569;
    }
    .garden-rect {
      flex: 1;
      max-width: 220px;
      height: 58px;
      background: linear-gradient(135deg, #f0fdf4 0%, #dcfce7 100%);
      border: 2px dashed #16a34a;
      border-radius: 8px;
      display: flex;
      align-items: center;
      justify-content: center;
    }
    .garden-rect span {
      font-size: 13px;
      font-weight: 700;
      color: #15803d;
    }

    /* Math typography */
    .math-row {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 12px;
      flex-wrap: wrap;
    }
    .math-item {
      display: flex;
      align-items: center;
      gap: 6px;
      font-size: 15px;
      font-weight: 700;
      color: #1e2945;
    }
    .arrow {
      color: #475569;
      font-size: 15px;
      font-weight: 700;
    }

    /* Fractions */
    .frac {
      display: inline-flex;
      flex-direction: column;
      vertical-align: middle;
      text-align: center;
      font-size: 13px;
      line-height: 1;
      padding: 0 2px;
      font-weight: 700;
    }
    .frac-top {
      border-bottom: 1.5px solid #1e2945;
      padding-bottom: 2px;
    }
    .frac-bot {
      padding-top: 2px;
    }
    .frac-colored {
      color: #0284c7;
    }
    .frac-colored .frac-top {
      border-bottom-color: #0284c7;
    }
    .mixed {
      display: inline-flex;
      align-items: center;
      gap: 2px;
      font-size: 15px;
      font-weight: 700;
    }

    /* Multiply row */
    .mult-row {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      font-size: 15px;
      font-weight: 700;
      color: #1e2945;
    }
    .mult-frac {
      font-size: 13px;
    }

    /* Result Badge */
    .result-badge {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      background: #e0f2fe;
      border: 1.5px solid #38bdf8;
      border-radius: 8px;
      padding: 5px 12px;
      color: #0369a1;
      font-weight: 700;
    }
    .result-badge .mixed {
      font-size: 16px;
      color: #0284c7;
    }
    .result-badge .mixed .frac-top {
      border-bottom-color: #0284c7;
    }

    .step-section {
      transition: opacity 0.2s ease;
    }
    .step-muted {
      opacity: 0.65;
    }
  </style>
</head>
<body>

  <div class="stepper-nav">
    <button class="step-btn active" onclick="setStep(0)" id="btn-0">1. Improper</button>
    <button class="step-btn" onclick="setStep(1)" id="btn-1">2. Multiply</button>
    <button class="step-btn" onclick="setStep(2)" id="btn-2">3. Area</button>
  </div>

  <div class="cards-container">
    
    <div class="math-card" id="card-diag">
      <div class="card-header">
        <span class="card-title">Garden Bed Dimensions</span>
        <span class="dim-sub" style="font-weight:700; color:#334155;">Area = Length × Width</span>
      </div>
      <div class="garden-visual-wrapper">
        
        <div class="dim-top">
          <span class="dim-label">Length: <span class="mixed">2<span class="frac"><span class="frac-top">1</span><span class="frac-bot">2</span></span></span> yd</span>
          <span class="dim-sub">(<span class="frac"><span class="frac-top">5</span><span class="frac-bot">2</span></span>)</span>
        </div>
        <div class="garden-main-row">
          
          <div class="dim-left">
            <div class="dim-label"><span class="mixed">1<span class="frac"><span class="frac-top">3</span><span class="frac-bot">4</span></span></span> yd</div>
            <div class="dim-sub">(<span class="frac"><span class="frac-top">7</span><span class="frac-bot">4</span></span>)</div>
          </div>
          <div class="garden-rect">
            <span>🌿 Garden Bed</span>
          </div>
          
          <div style="min-width: 65px;"></div>
        </div>
      </div>
    </div>

    
    <div class="math-card active-card" id="card-calc">
      <div id="step1-content" class="step-section">
        <div class="card-header">
          <span class="step-tag">Step 1</span>
          <span class="card-title">Convert to improper fractions</span>
        </div>
        <div class="math-row">
          <div class="math-item">
            <span class="mixed">2<span class="frac"><span class="frac-top">1</span><span class="frac-bot">2</span></span></span>
            <span class="arrow">→</span>
            <span class="frac frac-colored"><span class="frac-top">5</span><span class="frac-bot">2</span></span>
          </div>
          <div style="color:#475569; font-weight:700; font-size:13px;">and</div>
          <div class="math-item">
            <span class="mixed">1<span class="frac"><span class="frac-top">3</span><span class="frac-bot">4</span></span></span>
            <span class="arrow">→</span>
            <span class="frac frac-colored"><span class="frac-top">7</span><span class="frac-bot">4</span></span>
          </div>
        </div>
      </div>

      <div id="step2-content" class="step-section step-muted" style="margin-top: 8px; padding-top: 8px; border-top: 1px dashed #cbd5e1;">
        <div class="card-header">
          <span class="step-tag">Step 2</span>
          <span class="card-title">Multiply straight across</span>
        </div>
        <div class="mult-row">
          <div class="frac"><span class="frac-top">5</span><span class="frac-bot">2</span></div>
          <span>×</span>
          <div class="frac"><span class="frac-top">7</span><span class="frac-bot">4</span></div>
          <span>=</span>
          <div class="frac mult-frac">
            <span class="frac-top">5 × 7</span>
            <span class="frac-bot">2 × 4</span>
          </div>
          <span>=</span>
          <div class="frac frac-colored"><span class="frac-top">35</span><span class="frac-bot">8</span></div>
        </div>
      </div>
    </div>

    
    <div class="math-card dimmed" id="card-res">
      <div class="card-header">
        <span class="step-tag">Step 3</span>
        <span class="card-title">Convert to mixed number</span>
      </div>
      <div style="display: flex; align-items: center; justify-content: center; gap: 10px; flex-wrap: wrap;">
        <div class="math-item">
          <span class="frac"><span class="frac-top">35</span><span class="frac-bot">8</span></span>
          <span>=</span>
        </div>
        <div class="result-badge">
          <span class="mixed">4<span class="frac"><span class="frac-top">3</span><span class="frac-bot">8</span></span></span>
          <span>sq yd</span>
        </div>
      </div>
    </div>
  </div>

  <script>
    function setStep(idx) {
      const btns = [document.getElementById('btn-0'), document.getElementById('btn-1'), document.getElementById('btn-2')];
      btns.forEach((b, i) => b.classList.toggle('active', i === idx));

      const cardCalc = document.getElementById('card-calc');
      const cardRes = document.getElementById('card-res');
      const s1 = document.getElementById('step1-content');
      const s2 = document.getElementById('step2-content');

      if (idx === 0) {
        cardCalc.classList.add('active-card');
        cardCalc.classList.remove('dimmed');
        cardRes.classList.add('dimmed');
        cardRes.classList.remove('active-card');
        s1.classList.remove('step-muted');
        s2.classList.add('step-muted');
      } else if (idx === 1) {
        cardCalc.classList.add('active-card');
        cardCalc.classList.remove('dimmed');
        cardRes.classList.add('dimmed');
        cardRes.classList.remove('active-card');
        s1.classList.add('step-muted');
        s2.classList.remove('step-muted');
      } else {
        cardCalc.classList.remove('active-card');
        cardCalc.classList.add('dimmed');
        cardRes.classList.add('active-card');
        cardRes.classList.remove('dimmed');
        s1.classList.remove('step-muted');
        s2.classList.remove('step-muted');
      }
    }

    setStep(0);
  </script>
</body>
</html>

Solving Area Problems with Fractional Dimensions

<!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>Triangle Area with Fractional Dimensions</title>
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #ffffff;
      color: #1e2945;
      width: 100%;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
    }

    /* Top: Geometry Area */
    .geometry-box {
      width: 100%;
      max-width: 480px;
      display: flex;
      justify-content: center;
      align-items: center;
    }
    svg {
      width: 100%;
      max-height: 160px;
      overflow: visible;
    }

    /* Middle: Interactive Steps */
    .calc-container {
      width: 100%;
      max-width: 480px;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 12px 16px;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 10px;
      min-height: 130px;
      position: relative;
    }

    /* Math layout */
    .math-row {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      font-size: 18px;
      font-weight: 700;
      color: #1e2945;
      flex-wrap: wrap;
    }

    .frac {
      display: inline-flex;
      flex-direction: column;
      align-items: center;
      vertical-align: middle;
      padding: 0 3px;
      position: relative;
    }
    .num {
      border-bottom: 2px solid #1e2945;
      padding-bottom: 2px;
      width: 100%;
      text-align: center;
      position: relative;
    }
    .den {
      padding-top: 2px;
      width: 100%;
      text-align: center;
      position: relative;
    }

    /* Cross-canceling elements */
    .cross-val {
      position: relative;
      display: inline-block;
      transition: color 0.3s ease;
    }
    .strike {
      position: absolute;
      top: 50%;
      left: -2px;
      right: -2px;
      height: 2px;
      background: #ef4444;
      transform: rotate(-25deg);
      opacity: 0;
      transition: opacity 0.3s ease;
    }
    .sub-tag {
      position: absolute;
      font-size: 12px;
      font-weight: 800;
      opacity: 0;
      transition: opacity 0.3s ease, transform 0.3s ease;
    }
    .tag-top {
      top: -14px;
      left: 50%;
      transform: translateX(-50%) translateY(4px);
    }
    .tag-bottom {
      bottom: -14px;
      left: 50%;
      transform: translateX(-50%) translateY(-4px);
    }
    .tag-blue { color: #0284c7; }
    .tag-amber { color: #d97706; }

    /* Active cross-simplification states */
    .simplified .strike { opacity: 1; }
    .simplified .sub-tag {
      opacity: 1;
      transform: translateX(-50%) translateY(0);
    }
    .simplified .orig-num { color: #94a3b8; }

    /* Steps Display */
    .step-panel {
      display: none;
      width: 100%;
      text-align: center;
      animation: fadeIn 0.3s ease;
    }
    .step-panel.active {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 8px;
    }

    @keyframes fadeIn {
      from { opacity: 0; transform: translateY(3px); }
      to { opacity: 1; transform: translateY(0); }
    }

    /* Result Badge */
    .result-badge {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      background: #ecfdf5;
      border: 1.5px solid #10b981;
      color: #065f46;
      padding: 4px 12px;
      border-radius: 9999px;
      font-weight: 700;
      font-size: 16px;
    }

    /* Controls */
    .controls {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      width: 100%;
      max-width: 480px;
      margin-top: 4px;
    }
    .step-btn {
      background: #f1f5f9;
      border: 1px solid #cbd5e1;
      color: #475569;
      font-size: 13px;
      font-weight: 600;
      padding: 6px 14px;
      border-radius: 6px;
      cursor: pointer;
      transition: background 0.2s ease, color 0.2s ease, border-color 0.2s ease;
    }
    .step-btn:hover {
      background: #e2e8f0;
      color: #1e2945;
    }
    .step-btn.active {
      background: #0284c7;
      border-color: #0284c7;
      color: #ffffff;
    }

    .play-btn {
      background: #0284c7;
      border: none;
      color: white;
      width: 32px;
      height: 32px;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      font-size: 12px;
      transition: background 0.2s ease;
    }
    .play-btn:hover {
      background: #0369a1;
    }
  </style>
</head>
<body>

  
  <div class="geometry-box">
    <svg viewBox="0 0 360 145" aria-label="Right triangle inside bounding rectangle">
      <defs>
        
        <marker id="arrow" viewBox="0 0 10 10" refX="5" refY="5" markerWidth="4" markerHeight="4" orient="auto-start-reverse">
          <path d="M 0 1.5 L 8 5 L 0 8.5 z" fill="#64748b" />
        </marker>
      </defs>

      
      <rect x="70" y="20" width="200" height="95" fill="#f0f9ff" stroke="#93c5fd" stroke-width="1.5" stroke-dasharray="4 4" rx="2" />

      
      <polygon points="70,115 270,115 70,20" fill="#bae6fd" fill-opacity="0.6" stroke="#0284c7" stroke-width="2.5" stroke-linejoin="round" />

      
      <path d="M 70 101 L 84 101 L 84 115" fill="none" stroke="#0284c7" stroke-width="1.5" />

      
      <text x="130" y="78" font-size="12" font-weight="700" fill="#0369a1" opacity="0.8">½ of rectangle</text>

      
      <line x1="52" y1="22" x2="52" y2="113" stroke="#64748b" stroke-width="1.2" marker-start="url(#arrow)" marker-end="url(#arrow)" />
      <text x="44" y="68" font-size="13" font-weight="700" fill="#0f172a" text-anchor="end" dominant-baseline="middle">h = ⁹⁄₁₀ m</text>

      
      <line x1="72" y1="130" x2="268" y2="130" stroke="#64748b" stroke-width="1.2" marker-start="url(#arrow)" marker-end="url(#arrow)" />
      <text x="170" y="142" font-size="13" font-weight="700" fill="#0f172a" text-anchor="middle">b = ⁴⁄₃ m</text>
    </svg>
  </div>

  
  <div class="calc-container">

    
    <div id="step-0" class="step-panel active">
      <div class="math-row">
        <span>Area =</span>
        <div class="frac"><span class="num">1</span><span class="den">2</span></div>
        <span>×</span>
        <div class="frac"><span class="num">4</span><span class="den">3</span></div>
        <span>×</span>
        <div class="frac"><span class="num">9</span><span class="den">10</span></div>
      </div>
      <div style="font-size: 13px; color: #64748b; font-weight: 500;">
        Area = ½ × base × height
      </div>
    </div>

    
    <div id="step-1" class="step-panel">
      <div class="math-row simplified">
        <span>Area =</span>
        
        <div class="frac">
          <span class="num">1</span>
          <span class="den">
            <span class="cross-val">
              <span class="orig-num">2</span>
              <span class="strike"></span>
              <span class="sub-tag tag-bottom tag-blue">1</span>
            </span>
          </span>
        </div>
        <span>×</span>
        
        <div class="frac">
          <span class="num">
            <span class="cross-val">
              <span class="orig-num">4</span>
              <span class="strike"></span>
              <span class="sub-tag tag-top tag-blue">2</span>
            </span>
          </span>
          <span class="den">
            <span class="cross-val">
              <span class="orig-num">3</span>
              <span class="strike"></span>
              <span class="sub-tag tag-bottom tag-amber">1</span>
            </span>
          </span>
        </div>
        <span>×</span>
        
        <div class="frac">
          <span class="num">
            <span class="cross-val">
              <span class="orig-num">9</span>
              <span class="strike"></span>
              <span class="sub-tag tag-top tag-amber">3</span>
            </span>
          </span>
          <span class="den">10</span>
        </div>
      </div>
      <div style="font-size: 13px; color: #64748b; font-weight: 600;">
        Cross-simplify: <span style="color:#0284c7;">4 & 2 (÷2)</span> &nbsp;|&nbsp; <span style="color:#d97706;">9 & 3 (÷3)</span>
      </div>
    </div>

    
    <div id="step-2" class="step-panel">
      <div class="math-row">
        <span>Area =</span>
        <div class="frac">
          <span class="num">1 × 2 × 3</span>
          <span class="den">1 × 1 × 10</span>
        </div>
        <span>=</span>
        <div class="frac">
          <span class="num">6</span>
          <span class="den">10</span>
        </div>
      </div>
      <div style="font-size: 13px; color: #64748b; font-weight: 500;">
        Multiply remaining numerators & denominators
      </div>
    </div>

    
    <div id="step-3" class="step-panel">
      <div class="math-row">
        <span>Area =</span>
        <div class="frac" style="opacity: 0.6;">
          <span class="num">6</span>
          <span class="den">10</span>
        </div>
        <span>=</span>
        <div class="result-badge">
          <div class="frac" style="font-size: 18px;">
            <span class="num" style="border-color: #065f46;">3</span>
            <span class="den">5</span>
          </div>
          <span>m²</span>
        </div>
      </div>
      <div style="font-size: 13px; color: #059669; font-weight: 700;">
        ✓ Fully simplified area
      </div>
    </div>

  </div>

  
  <div class="controls">
    <button id="playBtn" class="play-btn" aria-label="Play/Pause">❚❚</button>
    <button class="step-btn active" data-step="0">1. Setup</button>
    <button class="step-btn" data-step="1">2. Simplify</button>
    <button class="step-btn" data-step="2">3. Multiply</button>
    <button class="step-btn" data-step="3">4. Result</button>
  </div>

  <script>
    const panels = document.querySelectorAll('.step-panel');
    const buttons = document.querySelectorAll('.step-btn');
    const playBtn = document.getElementById('playBtn');

    let currentStep = 0;
    let isPlaying = true;
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    }

    function nextStep() {
      showStep((currentStep + 1) % panels.length);
    }

    function startAutoPlay() {
      isPlaying = true;
      playBtn.textContent = '❚❚';
      clearInterval(timer);
      timer = setInterval(nextStep, 3500);
    }

    function pauseAutoPlay() {
      isPlaying = false;
      playBtn.textContent = '▶';
      clearInterval(timer);
    }

    buttons.forEach((btn, index) => {
      btn.addEventListener('click', () => {
        showStep(index);
        pauseAutoPlay();
      });
    });

    playBtn.addEventListener('click', () => {
      if (isPlaying) {
        pauseAutoPlay();
      } else {
        nextStep();
        startAutoPlay();
      }
    });

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

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="1:1">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      padding: 12px;
      min-height: 100%;
    }

    .wrapper {
      width: 100%;
      max-width: 400px;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 12px;
    }

    /* Controls */
    .controls {
      display: flex;
      gap: 6px;
      width: 100%;
      justify-content: center;
    }
    .btn {
      background: #f1f5f9;
      border: 1px solid #cbd5e1;
      border-radius: 6px;
      padding: 6px 12px;
      font-size: 13px;
      font-weight: 600;
      color: #475569;
      cursor: pointer;
      transition: background 0.2s, color 0.2s, border-color 0.2s;
    }
    .btn.active {
      background: #0284c7;
      color: #ffffff;
      border-color: #0284c7;
    }

    /* Grid Layout Container */
    .diagram-area {
      position: relative;
      width: 100%;
      display: grid;
      grid-template-columns: 44px 1fr;
      grid-template-rows: 40px 1fr;
      gap: 4px;
    }

    .corner-label {
      grid-column: 1;
      grid-row: 1;
    }

    /* Top Column Labels */
    .top-labels {
      grid-column: 2;
      grid-row: 1;
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      text-align: center;
      position: relative;
    }
    .col-header {
      font-size: 13px;
      font-weight: 700;
      color: #64748b;
      display: flex;
      flex-direction: column;
      justify-content: flex-end;
      padding-bottom: 4px;
      transition: color 0.2s;
    }
    .col-header.highlight {
      color: #0284c7;
    }
    .top-bracket {
      position: absolute;
      top: 0;
      left: 0;
      width: 75%;
      height: 18px;
      border-top: 2px solid #0284c7;
      border-left: 2px solid #0284c7;
      border-right: 2px solid #0284c7;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 12px;
      font-weight: 700;
      color: #0284c7;
      background: #ffffff;
      transform: translateY(-2px);
      border-radius: 3px 3px 0 0;
    }

    /* Left Row Labels */
    .left-labels {
      grid-column: 1;
      grid-row: 2;
      display: grid;
      grid-template-rows: repeat(3, 1fr);
      text-align: right;
      position: relative;
    }
    .row-header {
      font-size: 13px;
      font-weight: 700;
      color: #64748b;
      display: flex;
      align-items: center;
      justify-content: flex-end;
      padding-right: 8px;
      transition: color 0.2s;
    }
    .row-header.highlight {
      color: #0284c7;
    }
    .left-bracket {
      position: absolute;
      top: 0;
      left: 0;
      width: 14px;
      height: 66.66%;
      border-left: 2px solid #0284c7;
      border-top: 2px solid #0284c7;
      border-bottom: 2px solid #0284c7;
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: 3px 0 0 3px;
    }
    .left-bracket-text {
      writing-mode: vertical-rl;
      transform: rotate(180deg);
      font-size: 12px;
      font-weight: 700;
      color: #0284c7;
      margin-left: 2px;
    }

    /* Main Unit Grid (1 in x 1 in) */
    .grid-container {
      grid-column: 2;
      grid-row: 2;
      width: 100%;
      aspect-ratio: 4 / 3;
      background: #ffffff;
      border: 2px solid #94a3b8;
      border-radius: 4px;
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      grid-template-rows: repeat(3, 1fr);
      overflow: hidden;
      box-shadow: 0 1px 3px rgba(0,0,0,0.05);
    }

    .cell {
      border: 1px dashed #cbd5e1;
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: 700;
      font-size: 14px;
      color: transparent;
      transition: background-color 0.25s ease, color 0.25s ease;
      user-select: none;
    }

    /* Highlight states */
    .cell.shaded {
      background-color: rgba(34, 183, 255, 0.35);
      border: 1px solid rgba(2, 132, 199, 0.4);
      color: #0369a1;
    }
    .cell.col-active:not(.shaded) {
      background-color: rgba(34, 183, 255, 0.12);
    }
    .cell.row-active:not(.shaded) {
      background-color: rgba(34, 183, 255, 0.12);
    }

    .num-badge {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      width: 22px;
      height: 22px;
      border-radius: 50%;
      background: #0284c7;
      color: #ffffff;
      font-size: 12px;
      font-weight: 700;
    }

    /* Bottom Summary Card */
    .result-card {
      width: 100%;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      padding: 10px 14px;
      text-align: center;
      font-size: 14px;
      font-weight: 600;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      gap: 4px;
    }
    .math-expr {
      font-size: 15px;
      color: #0284c7;
      font-weight: 700;
    }
  </style>
</head>
<body>

  <div class="wrapper">
    
    <div class="controls">
      <button class="btn active" id="btnAll" onclick="setMode('overlap')">Overlap (Area)</button>
      <button class="btn" id="btnWidth" onclick="setMode('width')">Width (3/4)</button>
      <button class="btn" id="btnHeight" onclick="setMode('height')">Height (2/3)</button>
    </div>

    
    <div class="diagram-area">
      <div class="corner-label"></div>

      
      <div class="top-labels">
        <div class="top-bracket" id="topBracket">¾ in wide (3 cols)</div>
        <div class="col-header highlight" id="c0">¼</div>
        <div class="col-header highlight" id="c1">¼</div>
        <div class="col-header highlight" id="c2">¼</div>
        <div class="col-header" id="c3">¼</div>
      </div>

      
      <div class="left-labels">
        <div class="left-bracket" id="leftBracket">
          <span class="left-bracket-text">⅔ in</span>
        </div>
        <div class="row-header highlight" id="r0">⅓</div>
        <div class="row-header highlight" id="r1">⅓</div>
        <div class="row-header" id="r2">⅓</div>
      </div>

      
      <div class="grid-container" id="grid">
        
        <div class="cell shaded" data-r="0" data-c="0"><span class="num-badge">1</span></div>
        <div class="cell shaded" data-r="0" data-c="1"><span class="num-badge">2</span></div>
        <div class="cell shaded" data-r="0" data-c="2"><span class="num-badge">3</span></div>
        <div class="cell" data-r="0" data-c="3"></div>

        
        <div class="cell shaded" data-r="1" data-c="0"><span class="num-badge">4</span></div>
        <div class="cell shaded" data-r="1" data-c="1"><span class="num-badge">5</span></div>
        <div class="cell shaded" data-r="1" data-c="2"><span class="num-badge">6</span></div>
        <div class="cell" data-r="1" data-c="3"></div>

        
        <div class="cell" data-r="2" data-c="0"></div>
        <div class="cell" data-r="2" data-c="1"></div>
        <div class="cell" data-r="2" data-c="2"></div>
        <div class="cell" data-r="2" data-c="3"></div>
      </div>
    </div>

    
    <div class="result-card">
      <div id="statusText">6 out of 12 boxes shaded</div>
      <div class="math-expr" id="mathText">¾ × ⅔ = ⁶⁄₁₂ = ½ sq in</div>
    </div>
  </div>

  <script>
    const cells = document.querySelectorAll('.cell');
    const colHeaders = [document.getElementById('c0'), document.getElementById('c1'), document.getElementById('c2'), document.getElementById('c3')];
    const rowHeaders = [document.getElementById('r0'), document.getElementById('r1'), document.getElementById('r2')];
    const topBracket = document.getElementById('topBracket');
    const leftBracket = document.getElementById('leftBracket');
    const statusText = document.getElementById('statusText');
    const mathText = document.getElementById('mathText');

    function setMode(mode) {
      document.getElementById('btnAll').classList.toggle('active', mode === 'overlap');
      document.getElementById('btnWidth').classList.toggle('active', mode === 'width');
      document.getElementById('btnHeight').classList.toggle('active', mode === 'height');

      cells.forEach(cell => {
        const r = parseInt(cell.dataset.r);
        const c = parseInt(cell.dataset.c);
        cell.className = 'cell';

        if (mode === 'overlap') {
          if (r < 2 && c < 3) {
            cell.classList.add('shaded');
          }
        } else if (mode === 'width') {
          if (c < 3) {
            cell.classList.add('col-active');
          }
        } else if (mode === 'height') {
          if (r < 2) {
            cell.classList.add('row-active');
          }
        }
      });

      if (mode === 'overlap') {
        colHeaders.forEach((ch, idx) => ch.classList.toggle('highlight', idx < 3));
        rowHeaders.forEach((rh, idx) => rh.classList.toggle('highlight', idx < 2));
        topBracket.style.opacity = '1';
        leftBracket.style.opacity = '1';
        statusText.textContent = '6 out of 12 boxes shaded';
        mathText.textContent = '¾ × ⅔ = ⁶⁄₁₂ = ½ sq in';
      } else if (mode === 'width') {
        colHeaders.forEach((ch, idx) => ch.classList.toggle('highlight', idx < 3));
        rowHeaders.forEach(rh => rh.classList.remove('highlight'));
        topBracket.style.opacity = '1';
        leftBracket.style.opacity = '0.3';
        statusText.textContent = '3 out of 4 columns selected';
        mathText.textContent = 'Width = ¾ inch (9 of 12 tiles)';
      } else if (mode === 'height') {
        colHeaders.forEach(ch => ch.classList.remove('highlight'));
        rowHeaders.forEach((rh, idx) => rh.classList.toggle('highlight', idx < 2));
        topBracket.style.opacity = '0.3';
        leftBracket.style.opacity = '1';
        statusText.textContent = '2 out of 3 rows selected';
        mathText.textContent = 'Height = ⅔ inch (8 of 12 tiles)';
      }
    }
  </script>
</body>
</html>

111.26(b)(8)(D)

Aligned learning resources

Related diagrams