<!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: #ffffff;
      color: #1e2945;
      padding: 12px;
      display: flex;
      flex-direction: column;
      justify-content: center;
      gap: 14px;
      min-height: 100%;
    }

    .example-block {
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 12px 10px;
      display: flex;
      flex-direction: column;
      gap: 8px;
    }

    .math-row {
      display: flex;
      align-items: center;
      justify-content: center;
      flex-wrap: wrap;
      gap: 4px;
    }

    .badge-pair {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 4px;
      cursor: pointer;
      user-select: none;
      transition: transform 0.15s ease;
    }

    .badge-pair:active {
      transform: translateY(1px);
    }

    /* Roman Numeral Top Badge */
    .roman-badge {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      min-width: 38px;
      height: 38px;
      padding: 0 8px;
      border-radius: 8px;
      font-size: 18px;
      font-weight: 800;
      letter-spacing: 0.5px;
      border: 2px solid transparent;
      transition: filter 0.2s ease, box-shadow 0.2s ease;
    }

    /* Value Pill Bottom */
    .val-pill {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      min-width: 38px;
      height: 24px;
      padding: 0 6px;
      border-radius: 12px;
      font-size: 13px;
      font-weight: 700;
      border: 1px solid transparent;
      transition: filter 0.2s ease;
    }

    /* Operators (+ and =) */
    .op {
      font-size: 16px;
      font-weight: 700;
      color: #94a3b8;
      width: 14px;
      text-align: center;
      display: flex;
      align-items: center;
      justify-content: center;
      height: 38px;
    }

    /* Color Themes for Values */
    /* X = 10 (Cyan / Blue) */
    .c-x .roman-badge {
      background: #e0f2fe;
      color: #0369a1;
      border-color: #bae6fd;
    }
    .c-x .val-pill {
      background: #f0f9ff;
      color: #0284c7;
      border-color: #bae6fd;
    }

    /* V = 5 (Amber / Gold) */
    .c-v .roman-badge {
      background: #fef3c7;
      color: #b45309;
      border-color: #fde68a;
    }
    .c-v .val-pill {
      background: #fffbeb;
      color: #d97706;
      border-color: #fde68a;
    }

    /* I = 1 (Indigo / Purple) */
    .c-i .roman-badge {
      background: #ede9fe;
      color: #6d28d9;
      border-color: #ddd6fe;
    }
    .c-i .val-pill {
      background: #f5f3ff;
      color: #7c3aed;
      border-color: #ddd6fe;
    }

    /* Total / Result (Emerald Green) */
    .c-total .roman-badge {
      background: #dcfce7;
      color: #15803d;
      border-color: #86efac;
      min-width: 58px;
    }
    .c-total .val-pill {
      background: #f0fdf4;
      color: #16a34a;
      border-color: #86efac;
      min-width: 58px;
      font-size: 14px;
    }

    /* Interactive Highlight */
    .badge-pair.highlighted .roman-badge {
      box-shadow: 0 0 0 2px #3b82f6;
      filter: brightness(0.96);
    }
    .badge-pair.highlighted .val-pill {
      box-shadow: 0 0 0 1px #3b82f6;
      font-weight: 800;
    }

    @media (max-width: 380px) {
      body {
        padding: 8px;
        gap: 10px;
      }
      .example-block {
        padding: 10px 6px;
      }
      .roman-badge {
        min-width: 32px;
        height: 34px;
        font-size: 15px;
        padding: 0 4px;
      }
      .val-pill {
        min-width: 32px;
        height: 22px;
        font-size: 12px;
      }
      .c-total .roman-badge,
      .c-total .val-pill {
        min-width: 48px;
      }
      .op {
        font-size: 14px;
        width: 10px;
        height: 34px;
      }
    }
  </style>
</head>
<body>

  
  <div class="example-block">
    <div class="math-row">
      <div class="badge-pair c-v" title="V = 5">
        <div class="roman-badge">V</div>
        <div class="val-pill">5</div>
      </div>
      <div class="op">+</div>
      <div class="badge-pair c-i" title="I = 1">
        <div class="roman-badge">I</div>
        <div class="val-pill">1</div>
      </div>
      <div class="op">+</div>
      <div class="badge-pair c-i" title="I = 1">
        <div class="roman-badge">I</div>
        <div class="val-pill">1</div>
      </div>
      <div class="op">+</div>
      <div class="badge-pair c-i" title="I = 1">
        <div class="roman-badge">I</div>
        <div class="val-pill">1</div>
      </div>
      <div class="op">=</div>
      <div class="badge-pair c-total" title="VIII = 8">
        <div class="roman-badge">VIII</div>
        <div class="val-pill">8</div>
      </div>
    </div>
  </div>

  
  <div class="example-block">
    <div class="math-row">
      <div class="badge-pair c-x" title="X = 10">
        <div class="roman-badge">X</div>
        <div class="val-pill">10</div>
      </div>
      <div class="op">+</div>
      <div class="badge-pair c-x" title="X = 10">
        <div class="roman-badge">X</div>
        <div class="val-pill">10</div>
      </div>
      <div class="op">+</div>
      <div class="badge-pair c-v" title="V = 5">
        <div class="roman-badge">V</div>
        <div class="val-pill">5</div>
      </div>
      <div class="op">+</div>
      <div class="badge-pair c-i" title="I = 1">
        <div class="roman-badge">I</div>
        <div class="val-pill">1</div>
      </div>
      <div class="op">+</div>
      <div class="badge-pair c-i" title="I = 1">
        <div class="roman-badge">I</div>
        <div class="val-pill">1</div>
      </div>
      <div class="op">=</div>
      <div class="badge-pair c-total" title="XXVII = 27">
        <div class="roman-badge">XXVII</div>
        <div class="val-pill">27</div>
      </div>
    </div>
  </div>

  <script>
    document.querySelectorAll('.badge-pair').forEach(pair => {
      pair.addEventListener('click', () => {
        pair.classList.toggle('highlighted');
        setTimeout(() => {
          pair.classList.remove('highlighted');
        }, 1200);
      });
    });
  </script>
</body>
</html>

Understanding Basic Roman Numerals: I, V, X, and L

<!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;
      -webkit-tap-highlight-color: transparent;
    }

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: transparent;
      color: #1e293b;
      padding: 12px 8px;
      display: flex;
      flex-direction: column;
      gap: 12px;
      min-height: 100%;
      user-select: none;
    }

    /* Top Rule Banner */
    .header-bar {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 6px;
      text-align: center;
    }

    .rule-pill {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      background: #f1f5f9;
      border: 1px solid #cbd5e1;
      padding: 5px 14px;
      border-radius: 999px;
      font-size: 13px;
      font-weight: 700;
      color: #0f172a;
      letter-spacing: 0.2px;
    }

    .legend-row {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 6px;
      font-size: 12px;
      font-weight: 600;
    }

    .chip {
      padding: 2px 8px;
      border-radius: 6px;
      font-size: 11px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.5px;
    }
    .chip-base { background: #e0e7ff; color: #4338ca; border: 1px solid #c7d2fe; }
    .chip-sub { background: #fef3c7; color: #b45309; border: 1px solid #fde68a; }
    .chip-res { background: #d1fae5; color: #047857; border: 1px solid #a7f3d0; }

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

    .column-card {
      background: #ffffff;
      border: 2px solid #e2e8f0;
      border-radius: 14px;
      padding: 12px 8px;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 10px;
      cursor: pointer;
      box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
      transition: border-color 0.25s ease, box-shadow 0.25s ease, background-color 0.25s ease;
    }

    .column-card:hover, .column-card.active {
      border-color: #6366f1;
      box-shadow: 0 6px 14px -2px rgba(99, 102, 241, 0.18);
      background: #fafafa;
    }

    /* Numeral Visual Display */
    .numeral-group {
      display: flex;
      align-items: flex-start;
      justify-content: center;
      gap: 4px;
      margin-top: 2px;
    }

    .glyph-box {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 3px;
    }

    .glyph {
      font-family: "Times New Roman", Times, Georgia, serif;
      font-size: 32px;
      font-weight: 700;
      line-height: 1;
    }

    .badge {
      font-size: 11px;
      font-weight: 800;
      padding: 2px 6px;
      border-radius: 6px;
      line-height: 1.2;
    }

    .sub-val {
      color: #b45309;
      background: #fef3c7;
      border: 1px solid #fde68a;
    }

    .base-val {
      color: #4338ca;
      background: #e0e7ff;
      border: 1px solid #c7d2fe;
    }

    /* Subtraction Equation Box */
    .calc-box {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 4px;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      padding: 6px 8px;
      font-size: 15px;
      font-weight: 700;
      width: 100%;
      transition: background-color 0.2s ease, border-color 0.2s ease;
    }

    .column-card.active .calc-box {
      background: #ffffff;
      border-color: #cbd5e1;
    }

    .term-base { color: #4338ca; }
    .term-op { color: #64748b; font-weight: 600; }
    .term-sub { color: #b45309; }
    .term-eq { color: #64748b; font-weight: 600; }
    .term-res {
      color: #047857;
      background: #d1fae5;
      padding: 1px 6px;
      border-radius: 5px;
      border: 1px solid #a7f3d0;
    }

    /* Micro Reading Order Note */
    .reading-order {
      font-size: 11px;
      font-weight: 600;
      color: #475569;
      text-align: center;
      background: #f1f5f9;
      padding: 3px 6px;
      border-radius: 6px;
      width: 100%;
      min-height: 22px;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .column-card.active .reading-order {
      background: #ede9fe;
      color: #4338ca;
      font-weight: 700;
    }

    /* "Instead of" Not-Allowed Pill */
    .forbidden-pill {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 6px;
      background: #fef2f2;
      border: 1px dashed #fca5a5;
      border-radius: 6px;
      padding: 4px 6px;
      width: 100%;
      font-size: 11px;
      color: #991b1b;
      font-weight: 600;
    }

    .strike-text {
      text-decoration: line-through;
      font-family: "Times New Roman", Times, Georgia, serif;
      font-size: 13px;
      font-weight: 700;
      color: #dc2626;
      letter-spacing: 0.5px;
    }

    .cross-icon {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      width: 14px;
      height: 14px;
      background: #dc2626;
      color: #ffffff;
      border-radius: 50%;
      font-size: 9px;
      font-weight: 900;
      line-height: 1;
    }

    @media (max-width: 400px) {
      .glyph { font-size: 26px; }
      .calc-box { font-size: 13px; padding: 4px; }
      .chip { font-size: 9px; padding: 1px 4px; }
      .rule-pill { font-size: 12px; }
      .reading-order { font-size: 10px; }
    }
  </style>
</head>
<body>

  
  <div class="header-bar">
    <div class="rule-pill">Smaller Before Larger = Subtract</div>
    <div class="legend-row">
      <span class="chip chip-base">Base</span>
      <span>−</span>
      <span class="chip chip-sub">Subtracted</span>
      <span>=</span>
      <span class="chip chip-res">Result</span>
    </div>
  </div>

  
  <div class="grid">
    
    
    <div class="column-card active" onclick="activateCol(0)">
      <div class="numeral-group">
        <div class="glyph-box">
          <span class="glyph" style="color: #b45309;">I</span>
          <span class="badge sub-val">1</span>
        </div>
        <div class="glyph-box">
          <span class="glyph" style="color: #4338ca;">V</span>
          <span class="badge base-val">5</span>
        </div>
      </div>

      <div class="calc-box">
        <span class="term-base">5</span>
        <span class="term-op">−</span>
        <span class="term-sub">1</span>
        <span class="term-eq">=</span>
        <span class="term-res">4</span>
      </div>

      <div class="reading-order">1 before 5 → 4</div>

      <div class="forbidden-pill">
        <span class="strike-text">IIII</span>
        <span class="cross-icon">✕</span>
      </div>
    </div>

    
    <div class="column-card" onclick="activateCol(1)">
      <div class="numeral-group">
        <div class="glyph-box">
          <span class="glyph" style="color: #b45309;">I</span>
          <span class="badge sub-val">1</span>
        </div>
        <div class="glyph-box">
          <span class="glyph" style="color: #4338ca;">X</span>
          <span class="badge base-val">10</span>
        </div>
      </div>

      <div class="calc-box">
        <span class="term-base">10</span>
        <span class="term-op">−</span>
        <span class="term-sub">1</span>
        <span class="term-eq">=</span>
        <span class="term-res">9</span>
      </div>

      <div class="reading-order">1 before 10 → 9</div>

      <div class="forbidden-pill">
        <span class="strike-text">VIIII</span>
        <span class="cross-icon">✕</span>
      </div>
    </div>

    
    <div class="column-card" onclick="activateCol(2)">
      <div class="numeral-group">
        <div class="glyph-box">
          <span class="glyph" style="color: #b45309;">X</span>
          <span class="badge sub-val">10</span>
        </div>
        <div class="glyph-box">
          <span class="glyph" style="color: #4338ca;">L</span>
          <span class="badge base-val">50</span>
        </div>
      </div>

      <div class="calc-box">
        <span class="term-base">50</span>
        <span class="term-op">−</span>
        <span class="term-sub">10</span>
        <span class="term-eq">=</span>
        <span class="term-res">40</span>
      </div>

      <div class="reading-order">10 before 50 → 40</div>

      <div class="forbidden-pill">
        <span class="strike-text">XXXX</span>
        <span class="cross-icon">✕</span>
      </div>
    </div>

  </div>

  <script>
    function activateCol(index) {
      const cards = document.querySelectorAll('.column-card');
      cards.forEach((card, i) => {
        if (i === index) {
          card.classList.add('active');
        } else {
          card.classList.remove('active');
        }
      });
    }
  </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;
      background: #f8fafc;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100vh;
      padding: 16px;
      user-select: none;
    }

    .nav-tabs {
      display: flex;
      gap: 8px;
      margin-bottom: 16px;
      background: #e2e8f0;
      padding: 4px;
      border-radius: 999px;
    }

    .tab-btn {
      padding: 6px 18px;
      border: none;
      background: transparent;
      border-radius: 999px;
      font-size: 14px;
      font-weight: 700;
      color: #64748b;
      cursor: pointer;
      transition: all 0.25s ease;
    }

    .tab-btn.active {
      background: #ffffff;
      color: #0f172a;
      box-shadow: 0 2px 6px rgba(0,0,0,0.08);
    }

    .flow-card {
      width: 100%;
      max-width: 440px;
      background: #ffffff;
      border-radius: 16px;
      padding: 20px 16px;
      box-shadow: 0 4px 16px rgba(0,0,0,0.04);
      display: flex;
      flex-direction: column;
      align-items: center;
      position: relative;
    }

    /* Start / End Nodes */
    .node-pill {
      font-size: 20px;
      font-weight: 800;
      padding: 8px 24px;
      border-radius: 12px;
      background: #f1f5f9;
      color: #0f172a;
      border: 2px solid #cbd5e1;
      display: inline-flex;
      align-items: center;
      gap: 8px;
      transition: all 0.3s ease;
    }

    .node-result {
      background: #f0fdf4;
      border-color: #86efac;
      color: #15803d;
    }

    /* Middle split container */
    .split-row {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 16px;
      width: 100%;
      margin: 4px 0;
    }

    .part-box {
      border-radius: 14px;
      padding: 12px 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      transition: transform 0.3s ease;
    }

    .tens-box {
      background: #eff6ff;
      border: 2px solid #93c5fd;
      color: #1d4ed8;
    }

    .ones-box {
      background: #fff7ed;
      border: 2px solid #fdba74;
      color: #c2410c;
    }

    .val-main {
      font-size: 24px;
      font-weight: 800;
      line-height: 1.1;
    }

    .val-roman {
      font-size: 18px;
      font-weight: 700;
      margin-top: 4px;
      font-family: 'Times New Roman', serif;
      letter-spacing: 1px;
    }

    /* SVG connector area */
    .connector-svg {
      width: 100%;
      height: 38px;
      display: block;
    }

    .flow-line {
      fill: none;
      stroke-width: 2.5;
      stroke-linecap: round;
      stroke-dasharray: 4 4;
      animation: dash 15s linear infinite;
    }

    @keyframes dash {
      to { stroke-dashoffset: -200; }
    }

    .flow-blue { stroke: #3b82f6; }
    .flow-orange { stroke: #f97316; }

    .stepper-nav {
      display: flex;
      align-items: center;
      gap: 12px;
      margin-top: 16px;
    }

    .step-btn {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      color: #475569;
      font-size: 13px;
      font-weight: 600;
      padding: 6px 14px;
      border-radius: 8px;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 6px;
    }

    .step-btn:hover {
      background: #f8fafc;
      border-color: #94a3b8;
    }

    .step-dots {
      display: flex;
      gap: 6px;
    }

    .dot {
      width: 8px;
      height: 8px;
      border-radius: 50%;
      background: #cbd5e1;
      cursor: pointer;
      transition: all 0.25s ease;
    }

    .dot.active {
      background: #2563eb;
      width: 20px;
      border-radius: 4px;
    }
  </style>
</head>
<body>

  <div class="nav-tabs">
    <button class="tab-btn active" id="tab0" onclick="setExample(0)">34</button>
    <button class="tab-btn" id="tab1" onclick="setExample(1)">49</button>
  </div>

  <div class="flow-card">
    
    <div class="node-pill" id="sourceNum">34</div>

    
    <svg class="connector-svg" viewBox="0 0 300 40">
      <path class="flow-line flow-blue" d="M 150,2 C 150,20 75,10 75,38" />
      <path class="flow-line flow-orange" d="M 150,2 C 150,20 225,10 225,38" />
      <polygon points="75,38 71,30 79,30" fill="#3b82f6" />
      <polygon points="225,38 221,30 229,30" fill="#f97316" />
    </svg>

    
    <div class="split-row">
      <div class="part-box tens-box" id="tensBox">
        <span class="val-main" id="tensVal">30</span>
        <span class="val-roman" id="tensRoman">XXX</span>
      </div>
      <div class="part-box ones-box" id="onesBox">
        <span class="val-main" id="onesVal">4</span>
        <span class="val-roman" id="onesRoman">IV</span>
      </div>
    </div>

    
    <svg class="connector-svg" viewBox="0 0 300 40">
      <path class="flow-line flow-blue" d="M 75,2 C 75,25 150,15 150,38" />
      <path class="flow-line flow-orange" d="M 225,2 C 225,25 150,15 150,38" />
      <polygon points="150,38 146,30 154,30" fill="#15803d" />
    </svg>

    
    <div class="node-pill node-result" id="resultNum">
      <span style="font-family:'Times New Roman',serif; letter-spacing:1px;" id="resultRoman">XXXIV</span>
      <span>=</span>
      <span id="resultVal">34</span>
    </div>
  </div>

  <div class="stepper-nav">
    <div class="step-dots">
      <div class="dot active" id="dot0" onclick="setExample(0)"></div>
      <div class="dot" id="dot1" onclick="setExample(1)"></div>
    </div>
  </div>

  <script>
    const data = [
      { num: '34', tens: '30', tensR: 'XXX', ones: '4', onesR: 'IV', resR: 'XXXIV' },
      { num: '49', tens: '40', tensR: 'XL', ones: '9', onesR: 'IX', resR: 'XLIX' }
    ];

    let current = 0;

    function setExample(idx) {
      current = idx;
      const d = data[idx];

      document.getElementById('sourceNum').textContent = d.num;
      document.getElementById('tensVal').textContent = d.tens;
      document.getElementById('tensRoman').textContent = d.tensR;
      document.getElementById('onesVal').textContent = d.ones;
      document.getElementById('onesRoman').textContent = d.onesR;
      document.getElementById('resultRoman').textContent = d.resR;
      document.getElementById('resultVal').textContent = d.num;

      document.getElementById('tab0').classList.toggle('active', idx === 0);
      document.getElementById('tab1').classList.toggle('active', idx === 1);
      document.getElementById('dot0').classList.toggle('active', idx === 0);
      document.getElementById('dot1').classList.toggle('active', idx === 1);
    }
  </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;
      background: transparent;
      color: #1e2945;
      padding: 12px;
      display: flex;
      align-items: center;
      justify-content: center;
      min-height: 100%;
    }

    .grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 10px;
      width: 100%;
      max-width: 680px;
    }

    @media (max-width: 520px) {
      .grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 8px;
      }
    }

    .num-card {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 12px 6px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      box-shadow: 0 3px 10px rgba(0, 0, 0, 0.04);
      min-height: 170px;
      text-align: center;
    }

    .symbol {
      font-family: "Times New Roman", Times, serif;
      font-size: 38px;
      font-weight: 700;
      line-height: 1;
      margin-bottom: 2px;
    }

    .value {
      font-size: 15px;
      font-weight: 700;
      color: #475569;
      margin-bottom: 8px;
    }

    .visual-area {
      flex: 1;
      width: 100%;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    /* Symbol Color Themes */
    .card-i .symbol { color: #0284c7; }
    .card-v .symbol { color: #16a34a; }
    .card-x .symbol { color: #9333ea; }
    .card-l .symbol { color: #f97316; }

    /* Coin styling */
    .coin {
      width: 14px;
      height: 14px;
      background: radial-gradient(circle at 35% 35%, #fef08a, #eab308 60%, #ca8a04);
      border-radius: 50%;
      border: 1px solid #a16207;
      box-shadow: 0 1px 2px rgba(0,0,0,0.15);
      display: inline-block;
      flex-shrink: 0;
    }

    /* Card 1: Single Coin */
    .coin-single {
      width: 22px;
      height: 22px;
    }

    /* Card 2: Hand Shape (5 coins in a V/Hand arch) */
    .hand-layout {
      position: relative;
      width: 60px;
      height: 50px;
    }
    .hand-layout .coin {
      position: absolute;
    }
    .c-thumb  { left: 3px;  top: 24px; }
    .c-index  { left: 16px; top: 8px;  }
    .c-middle { left: 29px; top: 3px;  }
    .c-ring   { left: 42px; top: 10px; }
    .c-pinky  { left: 51px; top: 22px; }

    /* Card 3: 2 Rows of 5 */
    .ten-grid {
      display: grid;
      grid-template-columns: repeat(5, 12px);
      gap: 3px;
      justify-content: center;
    }
    .ten-grid .coin {
      width: 12px;
      height: 12px;
    }

    /* Card 4: 5 Stacks of 10 */
    .stacks-wrap {
      display: flex;
      gap: 3px;
      align-items: flex-end;
      justify-content: center;
      padding-top: 4px;
    }
    .stack {
      display: flex;
      flex-direction: column-reverse;
      position: relative;
      width: 13px;
      height: 48px;
    }
    .stack-coin {
      width: 13px;
      height: 6px;
      background: linear-gradient(180deg, #fef08a 0%, #eab308 50%, #ca8a04 100%);
      border: 1px solid #a16207;
      border-radius: 50%;
      position: absolute;
      left: 0;
    }
  </style>
</head>
<body>

  <div class="grid">
    
    <div class="num-card card-i">
      <div class="symbol">I</div>
      <div class="value">= 1</div>
      <div class="visual-area">
        <div class="coin coin-single"></div>
      </div>
    </div>

    
    <div class="num-card card-v">
      <div class="symbol">V</div>
      <div class="value">= 5</div>
      <div class="visual-area">
        <div class="hand-layout">
          <div class="coin c-thumb"></div>
          <div class="coin c-index"></div>
          <div class="coin c-middle"></div>
          <div class="coin c-ring"></div>
          <div class="coin c-pinky"></div>
        </div>
      </div>
    </div>

    
    <div class="num-card card-x">
      <div class="symbol">X</div>
      <div class="value">= 10</div>
      <div class="visual-area">
        <div class="ten-grid">
          <div class="coin"></div><div class="coin"></div><div class="coin"></div><div class="coin"></div><div class="coin"></div>
          <div class="coin"></div><div class="coin"></div><div class="coin"></div><div class="coin"></div><div class="coin"></div>
        </div>
      </div>
    </div>

    
    <div class="num-card card-l">
      <div class="symbol">L</div>
      <div class="value">= 50</div>
      <div class="visual-area">
        <div class="stacks-wrap" id="stacks"></div>
      </div>
    </div>
  </div>

  <script>
    // Generate 5 stacks of 10 layered coins for the 50 visual
    const stacksContainer = document.getElementById('stacks');
    for (let s = 0; s < 5; s++) {
      const stack = document.createElement('div');
      stack.className = 'stack';
      for (let c = 0; c < 10; c++) {
        const coin = document.createElement('div');
        coin.className = 'stack-coin';
        coin.style.bottom = (c * 4.2) + 'px';
        coin.style.zIndex = c + 1;
        stack.appendChild(coin);
      }
      stacksContainer.appendChild(stack);
    }
  </script>

</body>
</html>

OGM.5.NBT.6

Aligned learning resources

Related diagrams