<!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: #1e293b;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100%;
    }

    /* Tab switcher */
    .tabs {
      display: flex;
      gap: 8px;
      margin-bottom: 12px;
      background: #e2e8f0;
      padding: 3px;
      border-radius: 8px;
    }
    .tab-btn {
      border: none;
      background: transparent;
      padding: 6px 14px;
      font-size: 13px;
      font-weight: 600;
      color: #64748b;
      border-radius: 6px;
      cursor: pointer;
      transition: all 0.2s ease;
    }
    .tab-btn.active {
      background: #ffffff;
      color: #0f172a;
      box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    }

    /* Main Comparison Grid */
    .comparison-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 12px;
      width: 100%;
      max-width: 580px;
    }

    .column-panel {
      background: #ffffff;
      border-radius: 12px;
      padding: 12px 10px;
      border: 1.5px solid #e2e8f0;
      display: flex;
      flex-direction: column;
      align-items: center;
    }

    .column-panel.error-side {
      border-color: #fecaca;
      background: #fffafa;
    }

    .column-panel.correct-side {
      border-color: #bbf7d0;
      background: #f8fdf9;
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    .col-title {
      font-size: 13px;
      font-weight: 700;
      margin-bottom: 10px;
      text-align: center;
      display: flex;
      align-items: center;
      gap: 4px;
    }
    .error-side .col-title { color: #dc2626; }
    .correct-side .col-title { color: #16a34a; }

    /* Group Slot Containers */
    .slots-container {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 8px;
      width: 100%;
      margin-bottom: 10px;
    }

    .group-slot {
      display: flex;
      flex-direction: column;
      align-items: center;
      background: rgba(241, 245, 249, 0.7);
      border-radius: 8px;
      padding: 6px 4px;
      border: 1px dashed #cbd5e1;
    }

    .group-header {
      font-size: 11px;
      font-weight: 700;
      color: #475569;
      margin-bottom: 2px;
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    .group-sub {
      font-size: 10px;
      color: #94a3b8;
      margin-bottom: 6px;
    }

    /* Element Card */
    .element-card {
      width: 100%;
      background: #ffffff;
      border-radius: 6px;
      padding: 6px 4px;
      text-align: center;
      box-shadow: 0 1px 3px rgba(0,0,0,0.06);
      border: 1px solid #e2e8f0;
      transition: all 0.3s ease;
    }

    .element-card.chalcogen { border-top: 3px solid #f59e0b; }
    .element-card.halogen { border-top: 3px solid #8b5cf6; }
    .element-card.noble { border-top: 3px solid #06b6d4; }
    .element-card.alkali { border-top: 3px solid #ef4444; }

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      font-size: 18px;
      font-weight: 800;
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      line-height: 1.1;
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    .elem-name {
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    .elem-mass {
      font-size: 11px;
      font-weight: 700;
      color: #2563eb;
      margin-top: 2px;
    }

    /* Status Badges */
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      display: flex;
      align-items: center;
      justify-content: center;
      gap: 4px;
      font-size: 11px;
      font-weight: 700;
      padding: 4px 8px;
      border-radius: 20px;
      margin-top: auto;
      width: 100%;
    }

    .status-badge.bad {
      background: #fee2e2;
      color: #991b1b;
    }

    .status-badge.good {
      background: #dcfce7;
      color: #166534;
    }

    /* Mass anomaly callout */
    .anomaly-tag {
      font-size: 10px;
      font-weight: 700;
      color: #d97706;
      background: #fef3c7;
      border: 1px solid #fde68a;
      border-radius: 4px;
      padding: 2px 6px;
      margin-top: 6px;
      display: flex;
      align-items: center;
      gap: 4px;
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    @media (max-width: 440px) {
      .elem-symbol { font-size: 16px; }
      .elem-mass { font-size: 10px; }
      .col-title { font-size: 12px; }
      .slots-container { gap: 4px; }
    }
  </style>
</head>
<body>

  
  <div class="tabs">
    <button class="tab-btn active" id="tab-tei" onclick="switchPair('tei')">Pair 1: Te &amp; I</button>
    <button class="tab-btn" id="tab-ark" onclick="switchPair('ark')">Pair 2: Ar &amp; K</button>
  </div>

  
  <div class="comparison-grid">
    
    
    <div class="column-panel error-side">
      <div class="col-title">
        <span>❌ Strict Mass Order</span>
      </div>

      <div class="slots-container">
        
        <div class="group-slot">
          <div class="group-header" id="left-g1-title">Group 16</div>
          <div class="group-sub" id="left-g1-sub">Chalcogens</div>
          <div class="element-card" id="left-card-1">
            <div class="elem-symbol" id="left-sym-1">I</div>
            <div class="elem-name" id="left-name-1">Iodine</div>
            <div class="elem-mass" id="left-mass-1">126.9</div>
          </div>
        </div>

        
        <div class="group-slot">
          <div class="group-header" id="left-g2-title">Group 17</div>
          <div class="group-sub" id="left-g2-sub">Halogens</div>
          <div class="element-card" id="left-card-2">
            <div class="elem-symbol" id="left-sym-2">Te</div>
            <div class="elem-name" id="left-name-2">Tellurium</div>
            <div class="elem-mass" id="left-mass-2">127.6</div>
          </div>
        </div>
      </div>

      <div class="status-badge bad">
        ⚠️ Wrong Properties!
      </div>
    </div>

    
    <div class="column-panel correct-side">
      <div class="col-title">
        <span>✓ Property Order</span>
      </div>

      <div class="slots-container">
        
        <div class="group-slot">
          <div class="group-header" id="right-g1-title">Group 16</div>
          <div class="group-sub" id="right-g1-sub">Chalcogens</div>
          <div class="element-card" id="right-card-1">
            <div class="elem-symbol" id="right-sym-1">Te</div>
            <div class="elem-name" id="right-name-1">Tellurium</div>
            <div class="elem-mass" id="right-mass-1">127.6</div>
          </div>
        </div>

        
        <div class="group-slot">
          <div class="group-header" id="right-g2-title">Group 17</div>
          <div class="group-sub" id="right-g2-sub">Halogens</div>
          <div class="element-card" id="right-card-2">
            <div class="elem-symbol" id="right-sym-2">I</div>
            <div class="elem-name" id="right-name-2">Iodine</div>
            <div class="elem-mass" id="right-mass-2">126.9</div>
          </div>
        </div>
      </div>

      <div class="status-badge good">
        ✓ Matches Chemistry
      </div>
      <div class="anomaly-tag">
        ❓ Mass Reversal (127.6 → 126.9)
      </div>
    </div>

  </div>

  <script>
    const data = {
      tei: {
        g1Title: "Group 16",
        g1Sub: "Chalcogens",
        g2Title: "Group 17",
        g2Sub: "Halogens",
        left1: { sym: "I", name: "Iodine", mass: "126.9", type: "halogen" },
        left2: { sym: "Te", name: "Tellurium", mass: "127.6", type: "chalcogen" },
        right1: { sym: "Te", name: "Tellurium", mass: "127.6", type: "chalcogen" },
        right2: { sym: "I", name: "Iodine", mass: "126.9", type: "halogen" },
        anomaly: "❓ Mass Reversal (127.6 → 126.9)"
      },
      ark: {
        g1Title: "Group 18",
        g1Sub: "Noble Gases",
        g2Title: "Group 1",
        g2Sub: "Alkali Metals",
        left1: { sym: "K", name: "Potassium", mass: "39.10", type: "alkali" },
        left2: { sym: "Ar", name: "Argon", mass: "39.95", type: "noble" },
        right1: { sym: "Ar", name: "Argon", mass: "39.95", type: "noble" },
        right2: { sym: "K", name: "Potassium", mass: "39.10", type: "alkali" },
        anomaly: "❓ Mass Reversal (39.95 → 39.10)"
      }
    };

    function setCard(cardId, info) {
      const card = document.getElementById(cardId);
      card.className = "element-card " + info.type;
    }

    function switchPair(pairKey) {
      document.getElementById('tab-tei').classList.toggle('active', pairKey === 'tei');
      document.getElementById('tab-ark').classList.toggle('active', pairKey === 'ark');

      const d = data[pairKey];

      // Left column headers
      document.getElementById('left-g1-title').textContent = d.g1Title;
      document.getElementById('left-g1-sub').textContent = d.g1Sub;
      document.getElementById('left-g2-title').textContent = d.g2Title;
      document.getElementById('left-g2-sub').textContent = d.g2Sub;

      // Left cards
      document.getElementById('left-sym-1').textContent = d.left1.sym;
      document.getElementById('left-name-1').textContent = d.left1.name;
      document.getElementById('left-mass-1').textContent = d.left1.mass;
      setCard('left-card-1', d.left1);

      document.getElementById('left-sym-2').textContent = d.left2.sym;
      document.getElementById('left-name-2').textContent = d.left2.name;
      document.getElementById('left-mass-2').textContent = d.left2.mass;
      setCard('left-card-2', d.left2);

      // Right column headers
      document.getElementById('right-g1-title').textContent = d.g1Title;
      document.getElementById('right-g1-sub').textContent = d.g1Sub;
      document.getElementById('right-g2-title').textContent = d.g2Title;
      document.getElementById('right-g2-sub').textContent = d.g2Sub;

      // Right cards
      document.getElementById('right-sym-1').textContent = d.right1.sym;
      document.getElementById('right-name-1').textContent = d.right1.name;
      document.getElementById('right-mass-1').textContent = d.right1.mass;
      setCard('right-card-1', d.right1);

      document.getElementById('right-sym-2').textContent = d.right2.sym;
      document.getElementById('right-name-2').textContent = d.right2.name;
      document.getElementById('right-mass-2').textContent = d.right2.mass;
      setCard('right-card-2', d.right2);

      document.querySelector('.anomaly-tag').textContent = d.anomaly;
    }

    // Initialize
    switchPair('tei');
  </script>
</body>
</html>

Mendeleev, Moseley, and the Development of the Periodic Table

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Moseley's Law and X-Ray Spectroscopy</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      -webkit-tap-highlight-color: transparent;
    }
    body {
      background: #f8fafc;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      padding: 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-start;
      min-height: 100vh;
      user-select: none;
    }
    .header-formula {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 10px;
      margin-bottom: 8px;
      background: #ffffff;
      padding: 6px 16px;
      border-radius: 20px;
      border: 1px solid #e2e8f0;
      box-shadow: 0 1px 3px rgba(30,41,69,0.05);
    }
    .formula-tag {
      font-size: 15px;
      font-weight: 700;
      color: #0284c7;
      letter-spacing: 0.5px;
    }
    .main-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 10px;
      width: 100%;
      max-width: 620px;
    }
    @media (max-width: 520px) {
      .main-grid {
        grid-template-columns: 1fr;
      }
    }
    .panel {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      position: relative;
      overflow: hidden;
      display: flex;
      flex-direction: column;
      box-shadow: 0 1px 3px rgba(0,0,0,0.02);
    }
    .panel-title {
      font-size: 11px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.8px;
      color: #64748b;
      padding: 8px 10px 0 10px;
    }
    svg {
      width: 100%;
      height: auto;
      display: block;
    }
    .controls {
      display: flex;
      gap: 8px;
      justify-content: center;
      width: 100%;
      max-width: 620px;
      margin-top: 10px;
    }
    .elem-btn {
      flex: 1;
      padding: 6px 4px;
      font-size: 13px;
      font-weight: 700;
      border: 1px solid #cbd5e1;
      background: #ffffff;
      color: #1e2945;
      border-radius: 8px;
      cursor: pointer;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 2px;
      transition: background 0.15s, border-color 0.15s, color 0.15s;
    }
    .elem-btn span {
      font-size: 10px;
      font-weight: 500;
      color: #64748b;
    }
    .elem-btn.active {
      background: #0284c7;
      border-color: #0284c7;
      color: #ffffff;
    }
    .elem-btn.active span {
      color: #e0f2fe;
    }
    .plot-dot {
      cursor: pointer;
      transition: r 0.15s ease, fill 0.15s ease;
    }
    .wave-pulse {
      transition: opacity 0.2s ease;
    }
  </style>
</head>
<body>

  <div class="header-formula">
    <div class="formula-tag">Moseley's Law: √ν = a(Z − b)</div>
  </div>

  <div class="main-grid">
    
    <div class="panel">
      <div class="panel-title">X-Ray Spectroscopy Chamber</div>
      <svg viewBox="0 0 200 155" id="tubeSvg">
        <defs>
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            <stop offset="0%" stop-color="#00d2ff" stop-opacity="0.9" />
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          <linearGradient id="targetGrad" x1="0%" y1="0%" x2="100%" y2="100%">
            <stop offset="0%" stop-color="#cbd5e1" />
            <stop offset="100%" stop-color="#94a3b8" />
          </linearGradient>
        </defs>

        
        <rect x="8" y="24" width="184" height="106" rx="14" fill="#f8fafc" stroke="#e2e8f0" stroke-width="1.5" />

        
        <path d="M 12 77 L 22 77" stroke="#475569" stroke-width="3" stroke-linecap="round" />
        
        <path d="M 22 56 Q 30 77 22 98" fill="none" stroke="#475569" stroke-width="3.5" stroke-linecap="round" />
        
        <path d="M 20 68 Q 26 77 20 86" fill="none" stroke="#f59e0b" stroke-width="2" stroke-linecap="round" />
        <text x="24" y="44" font-size="8" font-weight="700" fill="#64748b" text-anchor="middle">Cathode (−)</text>

        
        
        <polygon points="24,72 88,68 88,86 24,82" fill="url(#beamGlow)" opacity="0.45" />
        
        <line x1="24" y1="74" x2="87" y2="74" stroke="#00d2ff" stroke-width="1.5" stroke-dasharray="4 3" />
        <line x1="24" y1="77" x2="88" y2="77" stroke="#00d2ff" stroke-width="2" stroke-dasharray="5 2" />
        <line x1="24" y1="80" x2="87" y2="80" stroke="#00d2ff" stroke-width="1.5" stroke-dasharray="4 3" />
        
        
        <polygon points="88,77 80,72 80,82" fill="#00d2ff" />
        
        
        <rect x="36" y="98" width="48" height="14" rx="3" fill="#ffffff" stroke="#cbd5e1" stroke-width="1" />
        <text x="60" y="108" font-size="7.5" font-weight="700" fill="#0284c7" text-anchor="middle">e⁻ Beam</text>

        
        <polygon points="88,48 110,70 110,106 88,84" fill="url(#targetGrad)" stroke="#64748b" stroke-width="1.2" />
        <polygon points="88,48 110,70 100,70 78,48" fill="#e2e8f0" />
        
        <rect x="110" y="72" width="22" height="10" fill="#94a3b8" />
        <text x="122" y="44" font-size="8" font-weight="700" fill="#64748b" text-anchor="middle">Anode (+)</text>

        
        <circle cx="88" cy="77" r="4.5" fill="#ff5757" opacity="0.8" />

        
        <path id="xrayWave" class="wave-pulse" d="M 94 69 Q 106 48 118 61 T 142 50 T 166 39 T 182 28" fill="none" stroke="#ff5757" stroke-width="2.5" stroke-linecap="round" />
        <polygon points="188,24 178,27 182,35" fill="#ff5757" />

        
        <text id="targetLabel" x="99" y="122" font-size="9.5" font-weight="700" fill="#ff5757" text-anchor="middle">Fe (Z=26)</text>
        <text id="freqLabel" x="154" y="20" font-size="9.5" font-weight="700" fill="#ff5757" text-anchor="middle">X-ray (ν)</text>
      </svg>
    </div>

    
    <div class="panel">
      <div class="panel-title">Moseley Plot (√ν vs Z)</div>
      <svg viewBox="0 0 200 155" id="graphSvg">
        
        
        <line x1="38" y1="120" x2="38" y2="18" stroke="#1e2945" stroke-width="1.5" />
        
        <line x1="38" y1="120" x2="190" y2="120" stroke="#1e2945" stroke-width="1.5" />
        
        
        <text x="38" y="13" font-size="9.5" font-weight="700" fill="#1e2945" text-anchor="middle">√ν</text>
        
        
        <text x="112" y="146" font-size="9" font-weight="700" fill="#1e2945" text-anchor="middle">Atomic Number (Z)</text>

        
        
        <line x1="42" y1="114" x2="167" y2="4" stroke="#00d2ff" stroke-width="1.8" stroke-dasharray="3 3" />

        
        <line id="projX" x1="67" y1="92" x2="67" y2="120" stroke="#ff5757" stroke-width="1" stroke-dasharray="2 2" />
        <line id="projY" x1="38" y1="92" x2="67" y2="92" stroke="#ff5757" stroke-width="1" stroke-dasharray="2 2" />

        
        
        <line x1="67" y1="120" x2="67" y2="123" stroke="#1e2945" stroke-width="1" />
        <text x="67" y="132" font-size="8" font-weight="600" fill="#64748b" text-anchor="middle">26</text>
        <circle id="dot-0" class="plot-dot" cx="67" cy="92" r="5" fill="#ff5757" stroke="#ffffff" stroke-width="1.5" onclick="selectElem(0)" />

        
        <line x1="92" y1="120" x2="92" y2="123" stroke="#1e2945" stroke-width="1" />
        <text x="92" y="132" font-size="8" font-weight="600" fill="#64748b" text-anchor="middle">27</text>
        <circle id="dot-1" class="plot-dot" cx="92" cy="70" r="4" fill="#0284c7" stroke="#ffffff" stroke-width="1.5" onclick="selectElem(1)" />

        
        <line x1="117" y1="120" x2="117" y2="123" stroke="#1e2945" stroke-width="1" />
        <text x="117" y="132" font-size="8" font-weight="600" fill="#64748b" text-anchor="middle">28</text>
        <circle id="dot-2" class="plot-dot" cx="117" cy="48" r="4" fill="#0284c7" stroke="#ffffff" stroke-width="1.5" onclick="selectElem(2)" />

        
        <line x1="142" y1="120" x2="142" y2="123" stroke="#1e2945" stroke-width="1" />
        <text x="142" y="132" font-size="8" font-weight="600" fill="#64748b" text-anchor="middle">29</text>
        <circle id="dot-3" class="plot-dot" cx="142" cy="26" r="4" fill="#0284c7" stroke="#ffffff" stroke-width="1.5" onclick="selectElem(3)" />
      </svg>
    </div>
  </div>

  
  <div class="controls">
    <button class="elem-btn active" id="btn-0" onclick="selectElem(0)">Fe<span>Z = 26</span></button>
    <button class="elem-btn" id="btn-1" onclick="selectElem(1)">Co<span>Z = 27</span></button>
    <button class="elem-btn" id="btn-2" onclick="selectElem(2)">Ni<span>Z = 28</span></button>
    <button class="elem-btn" id="btn-3" onclick="selectElem(3)">Cu<span>Z = 29</span></button>
  </div>

  <script>
    const elements = [
      { name: "Fe", z: 26, cx: 67, cy: 92 },
      { name: "Co", z: 27, cx: 92, cy: 70 },
      { name: "Ni", z: 28, cx: 117, cy: 48 },
      { name: "Cu", z: 29, cx: 142, cy: 26 }
    ];

    function selectElem(index) {
      const el = elements[index];

      // Update button and dot states
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        const btn = document.getElementById("btn-" + i);
        const dot = document.getElementById("dot-" + i);
        if (i === index) {
          btn.classList.add("active");
          dot.setAttribute("r", "5.5");
          dot.setAttribute("fill", "#ff5757");
        } else {
          btn.classList.remove("active");
          dot.setAttribute("r", "4");
          dot.setAttribute("fill", "#0284c7");
        }
      }

      // Update Labels
      document.getElementById("targetLabel").textContent = el.name + " (Z=" + el.z + ")";
      
      // Update Graph Projection lines
      const projX = document.getElementById("projX");
      const projY = document.getElementById("projY");

      projX.setAttribute("x1", el.cx);
      projX.setAttribute("y1", el.cy);
      projX.setAttribute("x2", el.cx);
      projX.setAttribute("y2", 120);

      projY.setAttribute("x1", 38);
      projY.setAttribute("y1", el.cy);
      projY.setAttribute("x2", el.cx);
      projY.setAttribute("y2", el.cy);

      // Trigger wave pulse visual effect
      const wave = document.getElementById("xrayWave");
      wave.style.opacity = "0.3";
      setTimeout(() => { wave.style.opacity = "1"; }, 120);
    }
  </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>Mendeleev Prediction vs Discovery</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      background: #f8f9fa;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100%;
    }
    .diagram-wrap {
      width: 100%;
      max-width: 600px;
      display: flex;
      flex-direction: column;
      gap: 10px;
    }
    .columns-header {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 10px;
    }
    .col-header {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 10px 12px;
      display: flex;
      align-items: center;
      gap: 10px;
      box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
    }
    .col-header.pred {
      border-left: 4px solid #0ea5e9;
    }
    .col-header.actual {
      border-left: 4px solid #10b981;
    }
    .avatar-icon {
      width: 32px;
      height: 32px;
      border-radius: 8px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: 700;
      font-size: 14px;
      flex-shrink: 0;
    }
    .avatar-icon.teal {
      background: #e0f2fe;
      color: #0369a1;
    }
    .avatar-icon.emerald {
      background: #d1fae5;
      color: #047857;
    }
    .col-title {
      font-size: 13px;
      font-weight: 700;
      line-height: 1.2;
    }
    .col-sub {
      font-size: 11px;
      color: #64748b;
    }
    .rows-container {
      display: flex;
      flex-direction: column;
      gap: 8px;
    }
    .prop-row {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 8px 12px;
      display: grid;
      grid-template-columns: 1fr auto 1fr;
      align-items: center;
      gap: 8px;
      cursor: pointer;
      user-select: none;
      transition: border-color 0.2s ease, box-shadow 0.2s ease;
      box-shadow: 0 1px 2px rgba(0, 0, 0, 0.03);
    }
    .prop-row:hover, .prop-row.active {
      border-color: #cbd5e1;
      box-shadow: 0 2px 6px rgba(0, 0, 0, 0.07);
    }
    .prop-row.active {
      border-color: #0ea5e9;
    }
    .val-box {
      display: flex;
      flex-direction: column;
    }
    .val-box.right {
      text-align: right;
      align-items: flex-end;
    }
    .prop-label {
      font-size: 10px;
      text-transform: uppercase;
      letter-spacing: 0.5px;
      font-weight: 700;
      color: #64748b;
      margin-bottom: 2px;
    }
    .prop-value {
      font-size: 15px;
      font-weight: 700;
      color: #1e2945;
    }
    .prop-value.teal {
      color: #0284c7;
    }
    .prop-value.emerald {
      color: #059669;
    }
    .match-pill {
      background: #d1fae5;
      color: #065f46;
      border-radius: 20px;
      padding: 4px 8px;
      font-size: 11px;
      font-weight: 700;
      display: flex;
      align-items: center;
      gap: 4px;
      white-space: nowrap;
    }
    .controls {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-top: 2px;
    }
    .tabs {
      display: flex;
      gap: 6px;
    }
    .tab-btn {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      color: #475569;
      padding: 5px 10px;
      border-radius: 6px;
      font-size: 11px;
      font-weight: 600;
      cursor: pointer;
      transition: background 0.15s ease, color 0.15s ease;
    }
    .tab-btn.active {
      background: #1e2945;
      color: #ffffff;
      border-color: #1e2945;
    }
    .status-text {
      font-size: 11px;
      color: #64748b;
      font-weight: 600;
    }
    @media (max-width: 420px) {
      .prop-value {
        font-size: 13px;
      }
      .prop-label {
        font-size: 9px;
      }
      .match-pill {
        font-size: 10px;
        padding: 3px 6px;
      }
      .col-header {
        padding: 8px;
      }
    }
  </style>
</head>
<body>
  <div class="diagram-wrap">
    <div class="columns-header">
      <div class="col-header pred">
        <div class="avatar-icon teal">Ea</div>
        <div>
          <div class="col-title">1871 Prediction</div>
          <div class="col-sub">Eka-aluminum</div>
        </div>
      </div>
      <div class="col-header actual">
        <div class="avatar-icon emerald">Ga</div>
        <div>
          <div class="col-title">1875 Discovery</div>
          <div class="col-sub">Gallium</div>
        </div>
      </div>
    </div>

    <div class="rows-container">
      <div class="prop-row active" data-index="0">
        <div class="val-box">
          <span class="prop-label">Atomic Mass</span>
          <span class="prop-value teal">~68 amu</span>
        </div>
        <div class="match-pill">✓ 69.72</div>
        <div class="val-box right">
          <span class="prop-label">Atomic Mass</span>
          <span class="prop-value emerald">69.72 amu</span>
        </div>
      </div>

      <div class="prop-row" data-index="1">
        <div class="val-box">
          <span class="prop-label">Density</span>
          <span class="prop-value teal">5.9 g/cm³</span>
        </div>
        <div class="match-pill">✓ 99.8%</div>
        <div class="val-box right">
          <span class="prop-label">Density</span>
          <span class="prop-value emerald">5.91 g/cm³</span>
        </div>
      </div>

      <div class="prop-row" data-index="2">
        <div class="val-box">
          <span class="prop-label">Melting Point</span>
          <span class="prop-value teal">Low</span>
        </div>
        <div class="match-pill">✓ 29.8°C</div>
        <div class="val-box right">
          <span class="prop-label">Melting Point</span>
          <span class="prop-value emerald">29.8°C</span>
        </div>
      </div>

      <div class="prop-row" data-index="3">
        <div class="val-box">
          <span class="prop-label">Oxide Formula</span>
          <span class="prop-value teal">Ea₂O₃</span>
        </div>
        <div class="match-pill">✓ Ga₂O₃</div>
        <div class="val-box right">
          <span class="prop-label">Oxide Formula</span>
          <span class="prop-value emerald">Ga₂O₃</span>
        </div>
      </div>
    </div>

    <div class="controls">
      <div class="tabs">
        <button class="tab-btn active" id="btnAll">All Properties</button>
        <button class="tab-btn" id="btnCycle">Step ▶</button>
      </div>
      <span class="status-text" id="statusInfo">4 of 4 Verified</span>
    </div>
  </div>

  <script>
    const rows = document.querySelectorAll('.prop-row');
    const btnAll = document.getElementById('btnAll');
    const btnCycle = document.getElementById('btnCycle');
    const statusInfo = document.getElementById('statusInfo');
    
    let currentIndex = -1;
    let timer = null;

    function selectRow(idx) {
      currentIndex = idx;
      rows.forEach((r, i) => {
        if (idx === -1 || idx === i) {
          r.style.opacity = '1';
          r.classList.toggle('active', idx === i);
        } else {
          r.style.opacity = '0.4';
          r.classList.remove('active');
        }
      });

      if (idx === -1) {
        btnAll.classList.add('active');
        btnCycle.classList.remove('active');
        statusInfo.textContent = '4 of 4 Verified';
      } else {
        btnAll.classList.remove('active');
        btnCycle.classList.add('active');
        statusInfo.textContent = `Property ${idx + 1} of 4`;
      }
    }

    rows.forEach((row, i) => {
      row.addEventListener('click', () => {
        clearInterval(timer);
        timer = null;
        btnCycle.textContent = 'Step ▶';
        selectRow(i);
      });
    });

    btnAll.addEventListener('click', () => {
      clearInterval(timer);
      timer = null;
      btnCycle.textContent = 'Step ▶';
      selectRow(-1);
    });

    btnCycle.addEventListener('click', () => {
      if (timer) {
        clearInterval(timer);
        timer = null;
        btnCycle.textContent = 'Step ▶';
      } else {
        btnCycle.textContent = 'Pause ⏸';
        stepNext();
        timer = setInterval(stepNext, 3000);
      }
    });

    function stepNext() {
      let next = currentIndex + 1;
      if (next >= rows.length || currentIndex === -1) {
        next = 0;
      }
      selectRow(next);
    }
  </script>
</body>
</html>

112.43(b)(5)(A)

Aligned learning resources

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