<!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;
      padding: 12px;
      display: flex;
      flex-direction: column;
      justify-content: center;
      min-height: 100%;
    }
    .grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 10px;
      width: 100%;
      max-width: 640px;
      margin: 0 auto;
    }
    @media (max-width: 500px) {
      .grid {
        grid-template-columns: 1fr;
        gap: 8px;
      }
    }
    .bench-card {
      background: #ffffff;
      border: 2px solid #e2e8f0;
      border-radius: 12px;
      padding: 12px 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
      cursor: pointer;
      transition: border-color 0.25s ease, box-shadow 0.25s ease;
    }
    .bench-card.active {
      border-color: #10b981;
      box-shadow: 0 0 0 3px rgba(16, 185, 129, 0.18);
    }
    .unit-tag {
      background: #ecfdf5;
      color: #047857;
      font-weight: 700;
      font-size: 14px;
      padding: 3px 8px;
      border-radius: 6px;
      margin-bottom: 6px;
    }
    .equiv {
      font-size: 13px;
      font-weight: 600;
      color: #64748b;
      min-height: 18px;
      margin-bottom: 8px;
    }
    .icons-row {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      font-size: 26px;
      margin: 4px 0 10px;
      line-height: 1;
    }
    .scale-track {
      width: 100%;
      height: 6px;
      background: #f1f5f9;
      border-radius: 3px;
      overflow: hidden;
      margin-top: auto;
    }
    .scale-fill {
      height: 100%;
      background: #10b981;
      border-radius: 3px;
      transition: width 0.4s ease;
    }
    .visual-comparison {
      margin-top: 10px;
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 8px 12px;
      max-width: 640px;
      width: 100%;
      margin-left: auto;
      margin-right: auto;
      display: flex;
      align-items: center;
      justify-content: space-between;
      font-size: 14px;
      font-weight: 600;
    }
    .comp-step {
      display: flex;
      align-items: center;
      gap: 6px;
    }
    .comp-arrow {
      color: #10b981;
      font-weight: 800;
    }
  </style>
</head>
<body>

  <div class="grid" id="cardGrid">
    
    <div class="bench-card active" onclick="selectCard(0)">
      <div class="unit-tag">1 Ounce (oz)</div>
      <div class="equiv">Base Unit</div>
      <div class="icons-row">
        <span>🍞</span>
        <span>🔋</span>
      </div>
      <div class="scale-track">
        <div class="scale-fill" style="width: 15%;"></div>
      </div>
    </div>

    
    <div class="bench-card" onclick="selectCard(1)">
      <div class="unit-tag">1 Pound (lb)</div>
      <div class="equiv">= 16 oz</div>
      <div class="icons-row">
        <span>🥖</span>
        <span>⚽</span>
      </div>
      <div class="scale-track">
        <div class="scale-fill" style="width: 55%;"></div>
      </div>
    </div>

    
    <div class="bench-card" onclick="selectCard(2)">
      <div class="unit-tag">1 Ton (T)</div>
      <div class="equiv">= 2,000 lbs</div>
      <div class="icons-row">
        <span>🚗</span>
        <span>🛻</span>
      </div>
      <div class="scale-track">
        <div class="scale-fill" style="width: 100%;"></div>
      </div>
    </div>
  </div>

  <div class="visual-comparison">
    <div class="comp-step"><span>1 oz</span></div>
    <div class="comp-arrow">× 16 →</div>
    <div class="comp-step"><span>1 lb</span></div>
    <div class="comp-arrow">× 2,000 →</div>
    <div class="comp-step"><span>1 T</span></div>
  </div>

  <script>
    function selectCard(index) {
      const cards = document.querySelectorAll('.bench-card');
      cards.forEach((card, idx) => {
        card.classList.toggle('active', idx === index);
      });
    }
  </script>
</body>
</html>

Understanding Imperial Units: Inches, Pounds and Pints

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

    /* Top interactive level tabs */
    .controls {
      display: flex;
      gap: 5px;
      width: 100%;
      max-width: 520px;
      justify-content: center;
      flex-wrap: wrap;
    }
    .level-btn {
      flex: 1 1 60px;
      padding: 6px 4px;
      background: #f8fafc;
      border: 1px solid #cbd5e1;
      border-radius: 8px;
      font-size: 12px;
      font-weight: 600;
      color: #475569;
      cursor: pointer;
      text-align: center;
      transition: background 0.2s, color 0.2s, box-shadow 0.2s, border-color 0.2s;
    }
    .level-btn.active {
      background: #7c3aed;
      color: #ffffff;
      border-color: #6d28d9;
      box-shadow: 0 2px 5px rgba(109, 40, 217, 0.25);
    }

    /* Diagram Tree Container */
    .tree-container {
      width: 100%;
      max-width: 520px;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 6px;
    }

    .tier {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 6px;
      width: 100%;
      transition: opacity 0.3s ease;
    }

    /* Wrap tiers when needed */
    .tier-pints {
      flex-wrap: wrap;
      gap: 4px;
    }

    .tier-cups {
      display: flex;
      flex-wrap: wrap;
      justify-content: center;
      gap: 4px 3px;
      width: 100%;
    }

    /* Tier Row Blocks */
    .unit-card {
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      background: #ffffff;
      border: 1.5px solid #cbd5e1;
      border-radius: 8px;
      padding: 4px 5px;
      cursor: pointer;
      transition: border-color 0.2s, background-color 0.2s, box-shadow 0.2s, opacity 0.2s;
      position: relative;
    }
    .unit-card.active-tier {
      border-color: #7c3aed;
      background: #f5f3ff;
      box-shadow: 0 0 0 1.5px rgba(124, 58, 237, 0.25);
    }
    .unit-card.dimmed {
      opacity: 0.35;
    }

    /* Specific sizing for levels */
    .card-gal {
      width: 120px;
      padding: 6px 10px;
    }
    .card-qt {
      flex: 1 1 0;
      max-width: 110px;
      min-width: 65px;
      padding: 5px 3px;
    }
    .card-pt {
      flex: 1 1 0;
      max-width: 55px;
      min-width: 34px;
      padding: 4px 2px;
    }
    .card-cp {
      flex: 1 1 calc(12.5% - 4px);
      max-width: 34px;
      min-width: 25px;
      padding: 3px 1px;
    }

    .unit-icon {
      font-size: 16px;
      line-height: 1.1;
    }
    .card-gal .unit-icon { font-size: 24px; }
    .card-qt .unit-icon { font-size: 18px; }
    .card-pt .unit-icon { font-size: 15px; }
    .card-cp .unit-icon { font-size: 12px; }

    .unit-label {
      font-size: 11px;
      font-weight: 700;
      margin-top: 1px;
      white-space: nowrap;
      color: #1e2945;
    }
    .card-pt .unit-label { font-size: 10px; }
    .card-cp .unit-label { font-size: 9.5px; }

    /* Darkened for strong contrast (>= 4.5:1) */
    .unit-sub {
      font-size: 10px;
      color: #6d28d9;
      font-weight: 700;
    }

    /* Connectors indicator between tiers */
    .divider-row {
      display: inline-flex;
      justify-content: center;
      align-items: center;
      font-size: 10.5px;
      font-weight: 700;
      color: #5b21b6;
      background: #ede9fe;
      border: 1px solid #ddd6fe;
      padding: 1px 9px;
      border-radius: 10px;
      align-self: center;
    }

    /* Math Summary Bar */
    .summary-card {
      width: 100%;
      max-width: 520px;
      background: #f8fafc;
      border: 1.5px solid #cbd5e1;
      border-radius: 9px;
      padding: 8px 12px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 6px;
      flex-wrap: wrap;
    }
    .summary-math {
      font-size: 13px;
      font-weight: 700;
      color: #0f172a;
      display: flex;
      align-items: center;
      gap: 4px;
      flex-wrap: wrap;
    }
    .summary-oz {
      font-size: 12.5px;
      font-weight: 700;
      color: #5b21b6;
    }

    @media (max-width: 380px) {
      body { padding: 6px; gap: 6px; }
      .level-btn { font-size: 11px; padding: 5px 2px; }
      .card-cp { flex: 1 1 calc(12.5% - 3px); min-width: 22px; padding: 2px 0; }
      .card-cp .unit-label { font-size: 9px; }
      .card-qt .unit-label { font-size: 10px; }
      .summary-card { padding: 6px 8px; }
      .summary-math { font-size: 12px; }
      .summary-oz { font-size: 12px; }
    }
  </style>
</head>
<body>

  
  <div class="controls">
    <button class="level-btn active" data-level="all">All Units</button>
    <button class="level-btn" data-level="gal">1 Gallon</button>
    <button class="level-btn" data-level="qt">4 Quarts</button>
    <button class="level-btn" data-level="pt">8 Pints</button>
    <button class="level-btn" data-level="cp">16 Cups</button>
  </div>

  
  <div class="tree-container">
    
    
    <div class="tier" id="tier-gal">
      <div class="unit-card card-gal active-tier" data-tier="gal">
        <span class="unit-icon">🪣</span>
        <span class="unit-label">1 Gallon</span>
        <span class="unit-sub">128 fl oz</span>
      </div>
    </div>

    <div class="divider-row">÷ 4 (4 Quarts)</div>

    
    <div class="tier" id="tier-qt">
      <div class="unit-card card-qt active-tier" data-tier="qt">
        <span class="unit-icon">🥛</span>
        <span class="unit-label">1 Quart</span>
        <span class="unit-sub">32 fl oz</span>
      </div>
      <div class="unit-card card-qt active-tier" data-tier="qt">
        <span class="unit-icon">🥛</span>
        <span class="unit-label">1 Quart</span>
        <span class="unit-sub">32 fl oz</span>
      </div>
      <div class="unit-card card-qt active-tier" data-tier="qt">
        <span class="unit-icon">🥛</span>
        <span class="unit-label">1 Quart</span>
        <span class="unit-sub">32 fl oz</span>
      </div>
      <div class="unit-card card-qt active-tier" data-tier="qt">
        <span class="unit-icon">🥛</span>
        <span class="unit-label">1 Quart</span>
        <span class="unit-sub">32 fl oz</span>
      </div>
    </div>

    <div class="divider-row">each ÷ 2 (8 Pints)</div>

    
    <div class="tier tier-pints" id="tier-pt">
      <div class="unit-card card-pt active-tier" data-tier="pt"><span class="unit-icon">🍨</span><span class="unit-label">1 Pt</span></div>
      <div class="unit-card card-pt active-tier" data-tier="pt"><span class="unit-icon">🍨</span><span class="unit-label">1 Pt</span></div>
      <div class="unit-card card-pt active-tier" data-tier="pt"><span class="unit-icon">🍨</span><span class="unit-label">1 Pt</span></div>
      <div class="unit-card card-pt active-tier" data-tier="pt"><span class="unit-icon">🍨</span><span class="unit-label">1 Pt</span></div>
      <div class="unit-card card-pt active-tier" data-tier="pt"><span class="unit-icon">🍨</span><span class="unit-label">1 Pt</span></div>
      <div class="unit-card card-pt active-tier" data-tier="pt"><span class="unit-icon">🍨</span><span class="unit-label">1 Pt</span></div>
      <div class="unit-card card-pt active-tier" data-tier="pt"><span class="unit-icon">🍨</span><span class="unit-label">1 Pt</span></div>
      <div class="unit-card card-pt active-tier" data-tier="pt"><span class="unit-icon">🍨</span><span class="unit-label">1 Pt</span></div>
    </div>

    <div class="divider-row">each ÷ 2 (16 Cups)</div>

    
    <div class="tier tier-cups" id="tier-cp">
      <div class="unit-card card-cp active-tier" data-tier="cp"><span class="unit-icon">☕</span><span class="unit-label">1 C</span></div>
      <div class="unit-card card-cp active-tier" data-tier="cp"><span class="unit-icon">☕</span><span class="unit-label">1 C</span></div>
      <div class="unit-card card-cp active-tier" data-tier="cp"><span class="unit-icon">☕</span><span class="unit-label">1 C</span></div>
      <div class="unit-card card-cp active-tier" data-tier="cp"><span class="unit-icon">☕</span><span class="unit-label">1 C</span></div>
      <div class="unit-card card-cp active-tier" data-tier="cp"><span class="unit-icon">☕</span><span class="unit-label">1 C</span></div>
      <div class="unit-card card-cp active-tier" data-tier="cp"><span class="unit-icon">☕</span><span class="unit-label">1 C</span></div>
      <div class="unit-card card-cp active-tier" data-tier="cp"><span class="unit-icon">☕</span><span class="unit-label">1 C</span></div>
      <div class="unit-card card-cp active-tier" data-tier="cp"><span class="unit-icon">☕</span><span class="unit-label">1 C</span></div>
      <div class="unit-card card-cp active-tier" data-tier="cp"><span class="unit-icon">☕</span><span class="unit-label">1 C</span></div>
      <div class="unit-card card-cp active-tier" data-tier="cp"><span class="unit-icon">☕</span><span class="unit-label">1 C</span></div>
      <div class="unit-card card-cp active-tier" data-tier="cp"><span class="unit-icon">☕</span><span class="unit-label">1 C</span></div>
      <div class="unit-card card-cp active-tier" data-tier="cp"><span class="unit-icon">☕</span><span class="unit-label">1 C</span></div>
      <div class="unit-card card-cp active-tier" data-tier="cp"><span class="unit-icon">☕</span><span class="unit-label">1 C</span></div>
      <div class="unit-card card-cp active-tier" data-tier="cp"><span class="unit-icon">☕</span><span class="unit-label">1 C</span></div>
      <div class="unit-card card-cp active-tier" data-tier="cp"><span class="unit-icon">☕</span><span class="unit-label">1 C</span></div>
      <div class="unit-card card-cp active-tier" data-tier="cp"><span class="unit-icon">☕</span><span class="unit-label">1 C</span></div>
    </div>

  </div>

  
  <div class="summary-card">
    <div class="summary-math" id="summaryMath">
      <span>1 Gallon = 4 Quarts = 8 Pints = 16 Cups</span>
    </div>
    <div class="summary-oz" id="summaryOz">1 Cup = 8 fl oz</div>
  </div>

  <script>
    const descriptions = {
      all: { math: "1 Gallon = 4 Quarts = 8 Pints = 16 Cups", oz: "1 Cup = 8 fl oz" },
      gal: { math: "1 Gallon (Jug) = 4 Quarts", oz: "= 128 Fluid Ounces (fl oz)" },
      qt: { math: "1 Quart (Carton) = 2 Pints", oz: "= 32 Fluid Ounces (fl oz)" },
      pt: { math: "1 Pint (Tub) = 2 Cups", oz: "= 16 Fluid Ounces (fl oz)" },
      cp: { math: "1 Cup (Measuring Cup)", oz: "= 8 Fluid Ounces (fl oz)" }
    };

    const buttons = document.querySelectorAll('.level-btn');
    const cards = document.querySelectorAll('.unit-card');
    const summaryMath = document.getElementById('summaryMath');
    const summaryOz = document.getElementById('summaryOz');

    function setLevel(lvl) {
      buttons.forEach(btn => {
        btn.classList.toggle('active', btn.dataset.level === lvl);
      });

      cards.forEach(card => {
        const tier = card.dataset.tier;
        if (lvl === 'all' || lvl === tier) {
          card.classList.remove('dimmed');
          card.classList.add('active-tier');
        } else {
          card.classList.add('dimmed');
          card.classList.remove('active-tier');
        }
      });

      const info = descriptions[lvl] || descriptions.all;
      summaryMath.innerHTML = info.math;
      summaryOz.innerHTML = info.oz;
    }

    buttons.forEach(btn => {
      btn.addEventListener('click', () => setLevel(btn.dataset.level));
    });

    cards.forEach(card => {
      card.addEventListener('click', () => {
        const tier = card.dataset.tier;
        const currentActive = document.querySelector('.level-btn.active')?.dataset.level;
        setLevel(currentActive === tier ? 'all' : tier);
      });
    });
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      background: transparent;
      padding: 12px;
      display: flex;
      flex-direction: column;
      gap: 10px;
    }

    .unit-selector {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 6px;
    }

    .unit-btn {
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      padding: 8px 4px;
      text-align: center;
      cursor: pointer;
      transition: background 0.2s, box-shadow 0.2s, border-color 0.2s;
      user-select: none;
    }

    .unit-btn.active {
      background: #f0f9ff;
      border-color: #38bdf8;
      box-shadow: 0 0 0 2px rgba(56, 189, 248, 0.35);
    }

    .unit-btn .title {
      font-size: 13px;
      font-weight: 700;
      color: #1e2945;
      line-height: 1.2;
    }

    .unit-btn .sub {
      font-size: 11px;
      color: #64748b;
      margin-top: 2px;
    }

    .display-area {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 16px;
      min-height: 240px;
      display: flex;
      flex-direction: column;
      justify-content: space-between;
      position: relative;
      overflow: hidden;
    }

    .card-panel {
      display: none;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 14px;
      width: 100%;
      height: 100%;
    }

    .card-panel.active {
      display: flex;
    }

    .header-badge {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      background: #f0f9ff;
      border: 1px solid #bae6fd;
      color: #0284c7;
      padding: 4px 12px;
      border-radius: 20px;
      font-size: 14px;
      font-weight: 700;
    }

    .benchmarks {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 16px;
      width: 100%;
      flex-wrap: wrap;
    }

    .bench-item {
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 12px 14px;
      min-width: 120px;
      flex: 1;
      max-width: 160px;
      text-align: center;
    }

    .bench-emoji {
      font-size: 32px;
      margin-bottom: 6px;
      line-height: 1;
    }

    .bench-label {
      font-size: 13px;
      font-weight: 600;
      color: #1e2945;
    }

    .scale-bar-container {
      width: 100%;
      background: #f1f5f9;
      border-radius: 6px;
      height: 24px;
      position: relative;
      overflow: hidden;
      display: flex;
      align-items: center;
      padding: 0 8px;
    }

    .scale-bar-fill {
      position: absolute;
      left: 0;
      top: 0;
      bottom: 0;
      background: linear-gradient(90deg, #38bdf8, #0284c7);
      border-radius: 6px;
      transition: width 0.4s ease;
    }

    .scale-caption {
      position: relative;
      z-index: 1;
      font-size: 11px;
      font-weight: 600;
      color: #0f172a;
      display: flex;
      justify-content: space-between;
      width: 100%;
    }

    .nav-row {
      display: flex;
      justify-content: center;
      align-items: center;
      gap: 8px;
    }

    .dot-btn {
      width: 8px;
      height: 8px;
      border-radius: 50%;
      background: #cbd5e1;
      border: none;
      cursor: pointer;
      padding: 0;
      transition: background 0.2s, transform 0.2s;
    }

    .dot-btn.active {
      background: #0284c7;
      transform: scale(1.3);
    }
  </style>
</head>
<body>

  <div class="unit-selector">
    <button class="unit-btn active" onclick="selectUnit(0)">
      <div class="title">Inch</div>
      <div class="sub">1 in</div>
    </button>
    <button class="unit-btn" onclick="selectUnit(1)">
      <div class="title">Foot</div>
      <div class="sub">12 in</div>
    </button>
    <button class="unit-btn" onclick="selectUnit(2)">
      <div class="title">Yard</div>
      <div class="sub">3 ft</div>
    </button>
    <button class="unit-btn" onclick="selectUnit(3)">
      <div class="title">Mile</div>
      <div class="sub">5,280 ft</div>
    </button>
  </div>

  <div class="display-area">
    
    <div class="card-panel active" id="panel-0">
      <div class="header-badge">1 Inch (in)</div>
      <div class="benchmarks">
        <div class="bench-item">
          <div class="bench-emoji">📎</div>
          <div class="bench-label">Paperclip</div>
        </div>
        <div class="bench-item">
          <div class="bench-emoji">👍</div>
          <div class="bench-label">Thumb Knuckle</div>
        </div>
      </div>
    </div>

    
    <div class="card-panel" id="panel-1">
      <div class="header-badge">1 Foot (ft) = 12 in</div>
      <div class="benchmarks">
        <div class="bench-item">
          <div class="bench-emoji">📏</div>
          <div class="bench-label">School Ruler</div>
        </div>
        <div class="bench-item">
          <div class="bench-emoji">📓</div>
          <div class="bench-label">Notebook Height</div>
        </div>
      </div>
    </div>

    
    <div class="card-panel" id="panel-2">
      <div class="header-badge">1 Yard (yd) = 3 ft</div>
      <div class="benchmarks">
        <div class="bench-item">
          <div class="bench-emoji">🚪</div>
          <div class="bench-label">Door Width</div>
        </div>
        <div class="bench-item">
          <div class="bench-emoji">🎸</div>
          <div class="bench-label">Guitar Length</div>
        </div>
      </div>
    </div>

    
    <div class="card-panel" id="panel-3">
      <div class="header-badge">1 Mile (mi) = 5,280 ft</div>
      <div class="benchmarks">
        <div class="bench-item">
          <div class="bench-emoji">🏃</div>
          <div class="bench-label">4 Track Laps</div>
        </div>
        <div class="bench-item">
          <div class="bench-emoji">⏱️</div>
          <div class="bench-label">20 min Walk</div>
        </div>
      </div>
    </div>

    
    <div class="scale-bar-container">
      <div class="scale-bar-fill" id="scaleFill" style="width: 2%;"></div>
      <div class="scale-caption">
        <span id="scaleMin">Smallest unit</span>
        <span id="scaleRatio">1 in</span>
      </div>
    </div>
  </div>

  <div class="nav-row">
    <button class="dot-btn active" onclick="selectUnit(0)" aria-label="Inch"></button>
    <button class="dot-btn" onclick="selectUnit(1)" aria-label="Foot"></button>
    <button class="dot-btn" onclick="selectUnit(2)" aria-label="Yard"></button>
    <button class="dot-btn" onclick="selectUnit(3)" aria-label="Mile"></button>
  </div>

  <script>
    const scaleWidths = ['5%', '25%', '55%', '100%'];
    const scaleTexts = ['1 in', '12 in', '36 in (3 ft)', '63,360 in (5,280 ft)'];

    let currentIndex = 0;

    function selectUnit(index) {
      currentIndex = index;
      const buttons = document.querySelectorAll('.unit-btn');
      const panels = document.querySelectorAll('.card-panel');
      const dots = document.querySelectorAll('.dot-btn');
      const fill = document.getElementById('scaleFill');
      const ratio = document.getElementById('scaleRatio');

      buttons.forEach((btn, i) => btn.classList.toggle('active', i === index));
      panels.forEach((p, i) => p.classList.toggle('active', i === index));
      dots.forEach((d, i) => d.classList.toggle('active', i === index));

      fill.style.width = scaleWidths[index];
      ratio.textContent = scaleTexts[index];
    }
  </script>
</body>
</html>

OGM.6.MD.2

Aligned learning resources

Related diagrams