<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: transparent;
      color: #1e293b;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-start;
      padding: 10px;
      min-height: 100%;
    }

    .main-wrapper {
      width: 100%;
      max-width: 680px;
      display: flex;
      flex-direction: column;
      gap: 10px;
    }

    .comparison-container {
      display: flex;
      flex-direction: row;
      gap: 12px;
      width: 100%;
      align-items: stretch;
    }

    .panel-box {
      display: flex;
      flex-direction: column;
      flex: 1;
    }

    .panel-box.panel-incorrect {
      flex: 1.25;
    }

    .badge-header {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      padding: 4px 10px;
      border-radius: 6px;
      font-size: 13px;
      font-weight: 700;
      letter-spacing: 0.4px;
      margin-bottom: 8px;
      align-self: flex-start;
    }

    .badge-correct-header {
      background: #dcfce7;
      color: #15803d;
    }

    .badge-incorrect-header {
      background: #fee2e2;
      color: #b91c1c;
    }

    .diagram-svg {
      width: 100%;
      height: auto;
      display: block;
    }

    /* Interactive hint/explanation panel */
    .info-callout {
      background: #f1f5f9;
      border-left: 4px solid #0284c7;
      padding: 8px 12px;
      border-radius: 0 6px 6px 0;
      font-size: 13px;
      line-height: 1.4;
      color: #334155;
      min-height: 38px;
      display: flex;
      align-items: center;
      transition: background-color 0.2s, border-color 0.2s;
    }

    .info-callout strong {
      margin-right: 4px;
    }

    /* SVG typography and styles */
    .spot-center-label {
      font-size: 12px;
      font-weight: 700;
      fill: #15803d;
    }

    .error-label {
      font-size: 11.5px;
      font-weight: 700;
      fill: #dc2626;
    }

    .baseline-label {
      font-size: 12px;
      font-weight: 600;
      fill: #64748b;
    }

    .clickable-group {
      cursor: pointer;
    }

    .clickable-group:focus {
      outline: none;
    }

    .clickable-group:hover ellipse {
      filter: drop-shadow(0 0 4px rgba(2, 132, 199, 0.5));
    }

    @media (max-width: 520px) {
      body {
        padding: 8px;
      }

      .comparison-container {
        flex-direction: column;
        gap: 16px;
      }

      .panel-box.panel-incorrect {
        flex: 1;
      }

      .info-callout {
        font-size: 12px;
      }
    }
  </style>
</head>
<body>

  <div class="main-wrapper">
    <div class="comparison-container">
      
      
      <div class="panel-box">
        <div class="badge-header badge-correct-header">
          <svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="3" stroke-linecap="round" stroke-linejoin="round">
            <polyline points="20 6 9 17 4 12"></polyline>
          </svg>
          CORRECT
        </div>

        <svg class="diagram-svg" viewBox="0 0 260 215" xmlns="http://www.w3.org/2000/svg" role="img" aria-label="Correct measurement method">
          <defs>
            <marker id="arrow-green" viewBox="0 0 10 10" refX="5" refY="5" markerWidth="5" markerHeight="5" orient="auto-start-reverse">
              <path d="M 0 1.5 L 10 5 L 0 8.5 z" fill="#16a34a" />
            </marker>
            <radialGradient id="spot-grad-1" cx="45%" cy="40%" r="55%">
              <stop offset="0%" stop-color="#38bdf8" />
              <stop offset="70%" stop-color="#0284c7" />
              <stop offset="100%" stop-color="#0369a1" />
            </radialGradient>
          </defs>

          
          <rect x="4" y="4" width="252" height="206" rx="6" fill="#f8fafc" stroke="#cbd5e1" stroke-width="1.5" />

          
          <g class="clickable-group" id="spot-correct-group" tabindex="0" role="button" aria-label="Center measurement example">
            
            <ellipse cx="175" cy="95" rx="28" ry="40" fill="url(#spot-grad-1)" />

            
            <line x1="135" y1="95" x2="215" y2="95" stroke="#ffffff" stroke-width="1.5" stroke-dasharray="3,2" />
            <line x1="175" y1="45" x2="175" y2="145" stroke="#ffffff" stroke-width="1.5" stroke-dasharray="3,2" />
            <circle cx="175" cy="95" r="3.5" fill="#ffffff" stroke="#0369a1" stroke-width="1.5" />
          </g>

          
          <line x1="72" y1="95" x2="175" y2="95" stroke="#16a34a" stroke-width="1.5" stroke-dasharray="3,3" />

          
          <line x1="12" y1="180" x2="248" y2="180" stroke="#64748b" stroke-width="2" />
          <text x="175" y="198" class="baseline-label" text-anchor="middle">Baseline</text>

          
          <line x1="72" y1="174" x2="72" y2="101" stroke="#16a34a" stroke-width="2.5" marker-start="url(#arrow-green)" marker-end="url(#arrow-green)" />
          <line x1="62" y1="180" x2="82" y2="180" stroke="#16a34a" stroke-width="2" />

          
          <text x="72" y="65" class="spot-center-label" text-anchor="middle">Distance</text>
          <text x="72" y="80" class="spot-center-label" text-anchor="middle">to center</text>
        </svg>
      </div>

      
      <div class="panel-box panel-incorrect">
        <div class="badge-header badge-incorrect-header">
          <svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="3" stroke-linecap="round" stroke-linejoin="round">
            <line x1="18" y1="6" x2="6" y2="18"></line>
            <line x1="6" y1="6" x2="18" y2="18"></line>
          </svg>
          INCORRECT
        </div>

        <svg class="diagram-svg" viewBox="0 0 330 215" xmlns="http://www.w3.org/2000/svg" role="img" aria-label="Incorrect measurement methods">
          <defs>
            <marker id="arrow-red" viewBox="0 0 10 10" refX="5" refY="5" markerWidth="5" markerHeight="5" orient="auto-start-reverse">
              <path d="M 0 1.5 L 10 5 L 0 8.5 z" fill="#dc2626" />
            </marker>
          </defs>

          
          <rect x="4" y="4" width="322" height="206" rx="6" fill="#f8fafc" stroke="#cbd5e1" stroke-width="1.5" />

          
          <g class="clickable-group" id="spot-bottom-group" tabindex="0" role="button" aria-label="Bottom edge measurement error">
            <ellipse cx="88" cy="95" rx="23" ry="34" fill="url(#spot-grad-1)" opacity="0.9" />
            <circle cx="88" cy="129" r="3" fill="#dc2626" />
          </g>

          
          <line x1="36" y1="129" x2="116" y2="129" stroke="#dc2626" stroke-width="1.5" stroke-dasharray="3,2" />

          
          <line x1="36" y1="174" x2="36" y2="135" stroke="#dc2626" stroke-width="2" marker-start="url(#arrow-red)" marker-end="url(#arrow-red)" />
          <line x1="28" y1="180" x2="44" y2="180" stroke="#dc2626" stroke-width="1.5" />

          
          <text x="36" y="104" class="error-label" text-anchor="middle">To bottom</text>
          <text x="36" y="118" class="error-label" text-anchor="middle">edge ✗</text>

          
          <g class="clickable-group" id="spot-top-group" tabindex="0" role="button" aria-label="Top edge measurement error">
            <ellipse cx="236" cy="95" rx="23" ry="34" fill="url(#spot-grad-1)" opacity="0.9" />
            <circle cx="236" cy="61" r="3" fill="#dc2626" />
          </g>

          
          <line x1="184" y1="61" x2="264" y2="61" stroke="#dc2626" stroke-width="1.5" stroke-dasharray="3,2" />

          
          <line x1="184" y1="174" x2="184" y2="67" stroke="#dc2626" stroke-width="2" marker-start="url(#arrow-red)" marker-end="url(#arrow-red)" />
          <line x1="176" y1="180" x2="192" y2="180" stroke="#dc2626" stroke-width="1.5" />

          
          <text x="184" y="42" class="error-label" text-anchor="middle">To top</text>
          <text x="184" y="55" class="error-label" text-anchor="middle">edge ✗</text>

          
          <line x1="12" y1="180" x2="318" y2="180" stroke="#64748b" stroke-width="2" />
          <text x="88" y="198" class="baseline-label" text-anchor="middle">Baseline</text>
          <text x="236" y="198" class="baseline-label" text-anchor="middle">Baseline</text>
        </svg>
      </div>

    </div>

    
    <div class="info-callout" id="info-text">
      <span><strong>Rule:</strong> Always measure from the baseline pencil line to the vertical center (point of highest concentration) of the spot, never to the edges.</span>
    </div>
  </div>

  <script>
    const infoText = document.getElementById('info-text');
    const spotCorrect = document.getElementById('spot-correct-group');
    const spotBottom = document.getElementById('spot-bottom-group');
    const spotTop = document.getElementById('spot-top-group');

    function updateInfo(type) {
      if (type === 'correct') {
        infoText.style.borderLeftColor = '#16a34a';
        infoText.style.backgroundColor = '#f0fdf4';
        infoText.innerHTML = '<span><strong style="color:#15803d;">✓ Correct:</strong> The distance traveled by a solute is measured from the baseline to the center (densest part) of the spot for an accurate Rf value.</span>';
      } else if (type === 'bottom') {
        infoText.style.borderLeftColor = '#dc2626';
        infoText.style.backgroundColor = '#fef2f2';
        infoText.innerHTML = '<span><strong style="color:#b91c1c;">✗ Error (Bottom edge):</strong> Measuring to the bottom edge underestimates the travel distance and leads to an incorrect, lower Rf value.</span>';
      } else if (type === 'top') {
        infoText.style.borderLeftColor = '#dc2626';
        infoText.style.backgroundColor = '#fef2f2';
        infoText.innerHTML = '<span><strong style="color:#b91c1c;">✗ Error (Top edge):</strong> Measuring to the top edge overestimates the travel distance and yields an erroneously high Rf value.</span>';
      }
    }

    spotCorrect.addEventListener('click', () => updateInfo('correct'));
    spotBottom.addEventListener('click', () => updateInfo('bottom'));
    spotTop.addEventListener('click', () => updateInfo('top'));

    spotCorrect.addEventListener('keydown', (e) => { if (e.key === 'Enter' || e.key === ' ') { updateInfo('correct'); e.preventDefault(); } });
    spotBottom.addEventListener('keydown', (e) => { if (e.key === 'Enter' || e.key === ' ') { updateInfo('bottom'); e.preventDefault(); } });
    spotTop.addEventListener('keydown', (e) => { if (e.key === 'Enter' || e.key === ' ') { updateInfo('top'); e.preventDefault(); } });
  </script>
</body>
</html>

Measuring Distances on a Chromatogram

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Chromatography Strip Measurement</title>
  <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;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-start;
      padding: 8px;
      user-select: none;
      min-height: auto;
    }
    .btn-group {
      display: flex;
      gap: 6px;
      margin-bottom: 6px;
      flex-wrap: wrap;
      justify-content: center;
      width: 100%;
      max-width: 520px;
    }
    .filter-btn {
      appearance: none;
      border: 1px solid #cbd5e1;
      background: #ffffff;
      color: #475569;
      font-size: 12px;
      font-weight: 600;
      padding: 5px 10px;
      border-radius: 6px;
      cursor: pointer;
      transition: background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
    }
    .filter-btn:hover {
      background: #f1f5f9;
      border-color: #94a3b8;
    }
    .filter-btn.active {
      background: #2563eb;
      color: #ffffff;
      border-color: #2563eb;
      box-shadow: 0 1px 4px rgba(37,99,235,0.3);
    }
    .svg-container {
      width: 100%;
      max-width: 520px;
      display: flex;
      justify-content: center;
    }
    svg {
      width: 100%;
      height: auto;
      display: block;
    }
    .dim-group {
      transition: opacity 0.2s ease;
      cursor: pointer;
    }
    .dim-group:hover rect {
      stroke-width: 1.5;
    }
    .dim-group.dimmed {
      opacity: 0.22;
    }
    .dim-group.highlight text {
      font-weight: 700;
    }
    .dim-group.highlight line {
      stroke-width: 2.2;
    }
  </style>
</head>
<body>

  <div class="btn-group">
    <button class="filter-btn active" onclick="selectTrack('all')">Show All</button>
    <button class="filter-btn" onclick="selectTrack('yellow')">Yellow (28 mm)</button>
    <button class="filter-btn" onclick="selectTrack('purple')">Purple (52 mm)</button>
    <button class="filter-btn" onclick="selectTrack('solvent')">Solvent (70 mm)</button>
  </div>

  <div class="svg-container">
    <svg viewBox="-85 8 585 368" xmlns="http://www.w3.org/2000/svg">
      <defs>
        
        <marker id="arrow-yellow" viewBox="0 0 6 6" refX="3" refY="3" markerWidth="5" markerHeight="5" orient="auto">
          <path d="M 0 1.5 L 3 3 L 0 4.5 z" fill="#d97706" />
        </marker>
        <marker id="arrow-yellow-rev" viewBox="0 0 6 6" refX="3" refY="3" markerWidth="5" markerHeight="5" orient="auto">
          <path d="M 3 1.5 L 0 3 L 3 4.5 z" fill="#d97706" />
        </marker>

        <marker id="arrow-purple" viewBox="0 0 6 6" refX="3" refY="3" markerWidth="5" markerHeight="5" orient="auto">
          <path d="M 0 1.5 L 3 3 L 0 4.5 z" fill="#9333ea" />
        </marker>
        <marker id="arrow-purple-rev" viewBox="0 0 6 6" refX="3" refY="3" markerWidth="5" markerHeight="5" orient="auto">
          <path d="M 3 1.5 L 0 3 L 3 4.5 z" fill="#9333ea" />
        </marker>

        <marker id="arrow-solvent" viewBox="0 0 6 6" refX="3" refY="3" markerWidth="5" markerHeight="5" orient="auto">
          <path d="M 0 1.5 L 3 3 L 0 4.5 z" fill="#0284c7" />
        </marker>
        <marker id="arrow-solvent-rev" viewBox="0 0 6 6" refX="3" refY="3" markerWidth="5" markerHeight="5" orient="auto">
          <path d="M 3 1.5 L 0 3 L 3 4.5 z" fill="#0284c7" />
        </marker>
      </defs>

      
      <rect x="15" y="20" width="80" height="350" rx="3" fill="#ffffff" stroke="#cbd5e1" stroke-width="1.5" />

      
      <line x1="15" y1="70" x2="95" y2="70" stroke="#0284c7" stroke-width="1.5" stroke-dasharray="3 2" />
      <text x="10" y="74" fill="#0284c7" font-size="11" font-weight="600" text-anchor="end">Solvent front</text>

      
      <ellipse cx="55" cy="142" rx="14" ry="9" fill="#a855f7" opacity="0.85" />
      <circle cx="55" cy="142" r="1.5" fill="#581c87" />

      
      <ellipse cx="55" cy="238" rx="13" ry="8" fill="#facc15" opacity="0.9" />
      <circle cx="55" cy="238" r="1.5" fill="#854d0e" />

      
      <line x1="15" y1="350" x2="95" y2="350" stroke="#475569" stroke-width="1.5" />
      <text x="10" y="354" fill="#475569" font-size="11" font-weight="600" text-anchor="end">Baseline</text>

      
      <g id="ruler">
        <rect x="102" y="22" width="40" height="340" fill="#fef08a" opacity="0.35" stroke="#94a3b8" stroke-width="1" />
        <line x1="102" y1="22" x2="102" y2="362" stroke="#475569" stroke-width="1.5" />
        <text x="122" y="20" font-size="11" font-weight="700" fill="#334155" text-anchor="middle">mm</text>

        
        
        
        <line x1="102" y1="350" x2="118" y2="350" stroke="#1e2945" stroke-width="1.5" />
        <text x="122" y="354" font-size="11" font-weight="600" fill="#1e2945">0</text>
        
        
        <line x1="102" y1="310" x2="116" y2="310" stroke="#1e2945" stroke-width="1.2" />
        <text x="120" y="314" font-size="10" fill="#475569">10</text>

        
        <line x1="102" y1="270" x2="116" y2="270" stroke="#1e2945" stroke-width="1.2" />
        <text x="120" y="274" font-size="10" fill="#475569">20</text>

        
        <line x1="102" y1="230" x2="116" y2="230" stroke="#1e2945" stroke-width="1.2" />
        <text x="120" y="234" font-size="10" fill="#475569">30</text>

        
        <line x1="102" y1="190" x2="116" y2="190" stroke="#1e2945" stroke-width="1.2" />
        <text x="120" y="194" font-size="10" fill="#475569">40</text>

        
        <line x1="102" y1="150" x2="116" y2="150" stroke="#1e2945" stroke-width="1.2" />
        <text x="120" y="154" font-size="10" fill="#475569">50</text>

        
        <line x1="102" y1="110" x2="116" y2="110" stroke="#1e2945" stroke-width="1.2" />
        <text x="120" y="114" font-size="10" fill="#475569">60</text>

        
        <line x1="102" y1="70" x2="118" y2="70" stroke="#1e2945" stroke-width="1.5" />
        <text x="122" y="74" font-size="11" font-weight="600" fill="#1e2945">70</text>

        
        <line x1="102" y1="30" x2="116" y2="30" stroke="#1e2945" stroke-width="1.2" />
        <text x="120" y="34" font-size="10" fill="#475569">80</text>

        
        <line x1="102" y1="330" x2="111" y2="330" stroke="#64748b" stroke-width="1" />
        <line x1="102" y1="290" x2="111" y2="290" stroke="#64748b" stroke-width="1" />
        <line x1="102" y1="250" x2="111" y2="250" stroke="#64748b" stroke-width="1" />
        <line x1="102" y1="210" x2="111" y2="210" stroke="#64748b" stroke-width="1" />
        <line x1="102" y1="170" x2="111" y2="170" stroke="#64748b" stroke-width="1" />
        <line x1="102" y1="130" x2="111" y2="130" stroke="#64748b" stroke-width="1" />
        <line x1="102" y1="90" x2="111" y2="90" stroke="#64748b" stroke-width="1" />
        <line x1="102" y1="50" x2="111" y2="50" stroke="#64748b" stroke-width="1" />

        
        <line x1="102" y1="346" x2="107" y2="346" stroke="#94a3b8" stroke-width="0.8" />
        <line x1="102" y1="342" x2="107" y2="342" stroke="#94a3b8" stroke-width="0.8" />
        <line x1="102" y1="338" x2="107" y2="338" stroke="#94a3b8" stroke-width="0.8" />
        <line x1="102" y1="334" x2="107" y2="334" stroke="#94a3b8" stroke-width="0.8" />
        <line x1="102" y1="326" x2="107" y2="326" stroke="#94a3b8" stroke-width="0.8" />
        <line x1="102" y1="322" x2="107" y2="322" stroke="#94a3b8" stroke-width="0.8" />
        <line x1="102" y1="318" x2="107" y2="318" stroke="#94a3b8" stroke-width="0.8" />
        <line x1="102" y1="314" x2="107" y2="314" stroke="#94a3b8" stroke-width="0.8" />

        
        <line x1="102" y1="246" x2="107" y2="246" stroke="#94a3b8" stroke-width="0.8" />
        <line x1="102" y1="242" x2="107" y2="242" stroke="#94a3b8" stroke-width="0.8" />
        <line x1="102" y1="238" x2="109" y2="238" stroke="#d97706" stroke-width="1.2" />
        <line x1="102" y1="234" x2="107" y2="234" stroke="#94a3b8" stroke-width="0.8" />

        
        <line x1="102" y1="146" x2="107" y2="146" stroke="#94a3b8" stroke-width="0.8" />
        <line x1="102" y1="142" x2="109" y2="142" stroke="#9333ea" stroke-width="1.2" />
        <line x1="102" y1="138" x2="107" y2="138" stroke="#94a3b8" stroke-width="0.8" />
        <line x1="102" y1="134" x2="107" y2="134" stroke="#94a3b8" stroke-width="0.8" />
      </g>

      
      
      <line x1="95" y1="350" x2="480" y2="350" stroke="#cbd5e1" stroke-width="1" stroke-dasharray="2 2" />

      
      <line x1="68" y1="238" x2="240" y2="238" stroke="#fde047" stroke-width="1" stroke-dasharray="3 2" />

      
      <line x1="69" y1="142" x2="355" y2="142" stroke="#d8b4fe" stroke-width="1" stroke-dasharray="3 2" />

      
      <line x1="95" y1="70" x2="480" y2="70" stroke="#bae6fd" stroke-width="1" stroke-dasharray="3 2" />

      
      <g id="dim-yellow" class="dim-group" onclick="selectTrack('yellow')">
        <line x1="195" y1="344" x2="195" y2="244" stroke="#d97706" stroke-width="1.8" marker-start="url(#arrow-yellow-rev)" marker-end="url(#arrow-yellow)" />
        <line x1="185" y1="350" x2="205" y2="350" stroke="#d97706" stroke-width="1.2" />
        <line x1="185" y1="238" x2="205" y2="238" stroke="#d97706" stroke-width="1.2" />
        <rect x="144" y="284" width="102" height="20" rx="4" fill="#fef3c7" stroke="#f59e0b" stroke-width="0.8" />
        <text x="195" y="298" font-size="11.5" font-weight="600" fill="#92400e" text-anchor="middle">Yellow: 28 mm</text>
      </g>

      
      <g id="dim-purple" class="dim-group" onclick="selectTrack('purple')">
        <line x1="310" y1="344" x2="310" y2="148" stroke="#9333ea" stroke-width="1.8" marker-start="url(#arrow-purple-rev)" marker-end="url(#arrow-purple)" />
        <line x1="300" y1="350" x2="320" y2="350" stroke="#9333ea" stroke-width="1.2" />
        <line x1="300" y1="142" x2="320" y2="142" stroke="#9333ea" stroke-width="1.2" />
        <rect x="259" y="236" width="102" height="20" rx="4" fill="#f3e8ff" stroke="#a855f7" stroke-width="0.8" />
        <text x="310" y="250" font-size="11.5" font-weight="600" fill="#6b21a8" text-anchor="middle">Purple: 52 mm</text>
      </g>

      
      <g id="dim-solvent" class="dim-group" onclick="selectTrack('solvent')">
        <line x1="425" y1="344" x2="425" y2="76" stroke="#0284c7" stroke-width="1.8" marker-start="url(#arrow-solvent-rev)" marker-end="url(#arrow-solvent)" />
        <line x1="415" y1="350" x2="435" y2="350" stroke="#0284c7" stroke-width="1.2" />
        <line x1="415" y1="70" x2="435" y2="70" stroke="#0284c7" stroke-width="1.2" />
        <rect x="372" y="200" width="106" height="20" rx="4" fill="#e0f2fe" stroke="#0284c7" stroke-width="0.8" />
        <text x="425" y="214" font-size="11.5" font-weight="600" fill="#0369a1" text-anchor="middle">Solvent: 70 mm</text>
      </g>
    </svg>
  </div>

  <script>
    function selectTrack(type) {
      const btns = document.querySelectorAll('.filter-btn');
      btns.forEach(b => b.classList.remove('active'));
      
      const dims = {
        yellow: document.getElementById('dim-yellow'),
        purple: document.getElementById('dim-purple'),
        solvent: document.getElementById('dim-solvent')
      };

      if (type === 'all') {
        btns[0].classList.add('active');
        dims.yellow.classList.remove('dimmed', 'highlight');
        dims.purple.classList.remove('dimmed', 'highlight');
        dims.solvent.classList.remove('dimmed', 'highlight');
      } else if (type === 'yellow') {
        btns[1].classList.add('active');
        dims.yellow.classList.remove('dimmed');
        dims.yellow.classList.add('highlight');
        dims.purple.classList.add('dimmed');
        dims.purple.classList.remove('highlight');
        dims.solvent.classList.add('dimmed');
        dims.solvent.classList.remove('highlight');
      } else if (type === 'purple') {
        btns[2].classList.add('active');
        dims.purple.classList.remove('dimmed');
        dims.purple.classList.add('highlight');
        dims.yellow.classList.add('dimmed');
        dims.yellow.classList.remove('highlight');
        dims.solvent.classList.add('dimmed');
        dims.solvent.classList.remove('highlight');
      } else if (type === 'solvent') {
        btns[3].classList.add('active');
        dims.solvent.classList.remove('dimmed');
        dims.solvent.classList.add('highlight');
        dims.yellow.classList.add('dimmed');
        dims.yellow.classList.remove('highlight');
        dims.purple.classList.add('dimmed');
        dims.purple.classList.remove('highlight');
      }
    }
  </script>
</body>
</html>

<!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 {
      width: 100%;
      min-height: 100%;
      background-color: #f8f9fa;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      user-select: none;
      padding: 12px;
    }
    .main-container {
      width: 100%;
      max-width: 480px;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 10px;
    }
    .nav-tabs {
      display: flex;
      gap: 6px;
      background: #e2e8f0;
      padding: 3px;
      border-radius: 8px;
    }
    .tab-btn {
      border: none;
      background: transparent;
      padding: 6px 14px;
      font-size: 13px;
      font-weight: 600;
      color: #475569;
      border-radius: 6px;
      cursor: pointer;
      transition: background-color 0.2s ease, color 0.2s ease, box-shadow 0.2s ease;
    }
    .tab-btn:hover {
      background: rgba(255, 255, 255, 0.6);
      color: #0f172a;
    }
    .tab-btn.active {
      background: #ffffff;
      color: #0f172a;
      box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    }
    svg {
      width: 100%;
      height: auto;
      display: block;
    }
    .label-text {
      font-size: 12px;
      font-weight: 600;
      fill: #334155;
    }
    .ruler-num {
      font-size: 9px;
      font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
      font-weight: 600;
      fill: #78350f;
      text-anchor: end;
      dominant-baseline: middle;
    }
    .dist-group {
      transition: opacity 0.2s ease;
      opacity: 0;
      pointer-events: none;
    }
    .dist-group.visible {
      opacity: 1;
      pointer-events: auto;
    }
    .interactive-mark {
      cursor: pointer;
    }
    .interactive-mark:hover .label-text {
      fill: #1d4ed8;
    }
  </style>
</head>
<body>
  <div class="main-container">
    <div class="nav-tabs" role="tablist" aria-label="Distance Views">
      <button class="tab-btn active" data-view="all">All</button>
      <button class="tab-btn" data-view="red">Red</button>
      <button class="tab-btn" data-view="blue">Blue</button>
      <button class="tab-btn" data-view="front">Solvent</button>
    </div>

    <svg viewBox="0 0 460 300" aria-label="Paper Chromatography Strip Measurement Diagram">
      <defs>
        <marker id="arrow-up" viewBox="0 0 10 10" refX="5" refY="5" markerWidth="4" markerHeight="4" orient="auto-start-reverse">
          <path d="M 0 8 L 5 2 L 10 8 z" fill="#2563eb"/>
        </marker>
        <marker id="arrow-down" viewBox="0 0 10 10" refX="5" refY="5" markerWidth="4" markerHeight="4" orient="auto-start-reverse">
          <path d="M 0 2 L 5 8 L 10 2 z" fill="#2563eb"/>
        </marker>
      </defs>

      
      
      <g transform="translate(16, 0)">
        <rect x="0" y="30" width="46" height="240" rx="3" fill="#fef3c7" stroke="#d97706" stroke-width="1"/>
        <text x="38" y="43" font-size="8" font-weight="700" fill="#92400e" text-anchor="end">mm</text>
        
        
        <line x1="30" y1="250" x2="46" y2="250" stroke="#78350f" stroke-width="1.5"/>
        <text x="26" y="250" class="ruler-num">0</text>
        
        
        <line x1="33" y1="225" x2="46" y2="225" stroke="#78350f" stroke-width="1"/>
        <text x="26" y="225" class="ruler-num">10</text>
        
        
        <line x1="33" y1="200" x2="46" y2="200" stroke="#78350f" stroke-width="1"/>
        <text x="26" y="200" class="ruler-num">20</text>
        
        
        <line x1="30" y1="175" x2="46" y2="175" stroke="#78350f" stroke-width="1.5"/>
        <text x="26" y="175" class="ruler-num">30</text>
        
        
        <line x1="33" y1="150" x2="46" y2="150" stroke="#78350f" stroke-width="1"/>
        <text x="26" y="150" class="ruler-num">40</text>
        
        
        <line x1="33" y1="125" x2="46" y2="125" stroke="#78350f" stroke-width="1"/>
        <text x="26" y="125" class="ruler-num">50</text>
        
        
        <line x1="30" y1="100" x2="46" y2="100" stroke="#78350f" stroke-width="1.5"/>
        <text x="26" y="100" class="ruler-num">60</text>
        
        
        <line x1="33" y1="75" x2="46" y2="75" stroke="#78350f" stroke-width="1"/>
        <text x="26" y="75" class="ruler-num">70</text>
        
        
        <line x1="30" y1="50" x2="46" y2="50" stroke="#78350f" stroke-width="1.5"/>
        <text x="26" y="50" class="ruler-num">80</text>

        
        <line x1="38" y1="237.5" x2="46" y2="237.5" stroke="#78350f" stroke-width="0.8"/>
        <line x1="38" y1="212.5" x2="46" y2="212.5" stroke="#78350f" stroke-width="0.8"/>
        <line x1="38" y1="187.5" x2="46" y2="187.5" stroke="#78350f" stroke-width="0.8"/>
        <line x1="38" y1="162.5" x2="46" y2="162.5" stroke="#78350f" stroke-width="0.8"/>
        <line x1="38" y1="137.5" x2="46" y2="137.5" stroke="#78350f" stroke-width="0.8"/>
        <line x1="38" y1="112.5" x2="46" y2="112.5" stroke="#78350f" stroke-width="0.8"/>
        <line x1="38" y1="87.5" x2="46" y2="87.5" stroke="#78350f" stroke-width="0.8"/>
        <line x1="38" y1="62.5" x2="46" y2="62.5" stroke="#78350f" stroke-width="0.8"/>
      </g>

      
      <g transform="translate(68, 0)">
        <rect x="0" y="30" width="105" height="240" rx="2" fill="#ffffff" stroke="#cbd5e1" stroke-width="1.2"/>

        
        <line x1="0" y1="50" x2="105" y2="50" stroke="#94a3b8" stroke-width="1.5" stroke-dasharray="3 2"/>

        
        <ellipse cx="52.5" cy="100" rx="14" ry="10" fill="#3b82f6" opacity="0.9"/>

        
        <ellipse cx="52.5" cy="175" rx="13" ry="9" fill="#ef4444" opacity="0.9"/>

        
        <line x1="0" y1="250" x2="105" y2="250" stroke="#64748b" stroke-width="1.8"/>

        
        <circle cx="52.5" cy="250" r="2.5" fill="#64748b"/>
      </g>

      
      
      <g class="interactive-mark" data-target="front">
        <line x1="173" y1="50" x2="192" y2="50" stroke="#94a3b8" stroke-width="1" stroke-dasharray="2 2"/>
        <text x="198" y="54" class="label-text">Solvent Front</text>
      </g>

      
      <g class="interactive-mark" data-target="blue">
        <line x1="173" y1="100" x2="192" y2="100" stroke="#93c5fd" stroke-width="1" stroke-dasharray="2 2"/>
        <circle cx="198" cy="100" r="4.5" fill="#3b82f6"/>
        <text x="210" y="104" class="label-text">Blue Spot</text>
      </g>

      
      <g class="interactive-mark" data-target="red">
        <line x1="173" y1="175" x2="192" y2="175" stroke="#fca5a5" stroke-width="1" stroke-dasharray="2 2"/>
        <circle cx="198" cy="175" r="4.5" fill="#ef4444"/>
        <text x="210" y="179" class="label-text">Red Spot</text>
      </g>

      
      <g class="interactive-mark" data-target="all">
        <line x1="173" y1="250" x2="192" y2="250" stroke="#64748b" stroke-width="1" stroke-dasharray="2 2"/>
        <text x="198" y="254" class="label-text">Baseline (Origin)</text>
      </g>

      
      
      <g id="dist-red" class="dist-group visible">
        <line x1="375" y1="250" x2="375" y2="175" stroke="#2563eb" stroke-width="1.5" marker-start="url(#arrow-down)" marker-end="url(#arrow-up)"/>
        <line x1="367" y1="250" x2="383" y2="250" stroke="#2563eb" stroke-width="1.2"/>
        <line x1="367" y1="175" x2="383" y2="175" stroke="#2563eb" stroke-width="1.2"/>
        <rect x="388" y="203" width="52" height="20" rx="4" fill="#eff6ff" stroke="#bfdbfe" stroke-width="1"/>
        <text x="414" y="217" font-size="11" font-weight="700" fill="#1d4ed8" text-anchor="middle">30 mm</text>
      </g>

      
      <g id="dist-blue" class="dist-group visible">
        <line x1="375" y1="250" x2="375" y2="100" stroke="#2563eb" stroke-width="1.5" marker-start="url(#arrow-down)" marker-end="url(#arrow-up)"/>
        <line x1="367" y1="250" x2="383" y2="250" stroke="#2563eb" stroke-width="1.2"/>
        <line x1="367" y1="100" x2="383" y2="100" stroke="#2563eb" stroke-width="1.2"/>
        <rect x="388" y="130" width="52" height="20" rx="4" fill="#eff6ff" stroke="#bfdbfe" stroke-width="1"/>
        <text x="414" y="144" font-size="11" font-weight="700" fill="#1d4ed8" text-anchor="middle">60 mm</text>
      </g>

      
      <g id="dist-front" class="dist-group visible">
        <line x1="375" y1="250" x2="375" y2="50" stroke="#2563eb" stroke-width="1.5" marker-start="url(#arrow-down)" marker-end="url(#arrow-up)"/>
        <line x1="367" y1="250" x2="383" y2="250" stroke="#2563eb" stroke-width="1.2"/>
        <line x1="367" y1="50" x2="383" y2="50" stroke="#2563eb" stroke-width="1.2"/>
        <rect x="388" y="65" width="52" height="20" rx="4" fill="#eff6ff" stroke="#bfdbfe" stroke-width="1"/>
        <text x="414" y="79" font-size="11" font-weight="700" fill="#1d4ed8" text-anchor="middle">80 mm</text>
      </g>
    </svg>
  </div>

  <script>
    const buttons = document.querySelectorAll('.tab-btn');
    const marks = document.querySelectorAll('.interactive-mark');
    const distRed = document.getElementById('dist-red');
    const distBlue = document.getElementById('dist-blue');
    const distFront = document.getElementById('dist-front');

    function showDistances(mode) {
      buttons.forEach(btn => {
        btn.classList.toggle('active', btn.dataset.view === mode);
      });

      if (mode === 'all') {
        distRed.classList.add('visible');
        distBlue.classList.add('visible');
        distFront.classList.add('visible');
      } else if (mode === 'red') {
        distRed.classList.add('visible');
        distBlue.classList.remove('visible');
        distFront.classList.remove('visible');
      } else if (mode === 'blue') {
        distRed.classList.remove('visible');
        distBlue.classList.add('visible');
        distFront.classList.remove('visible');
      } else if (mode === 'front') {
        distRed.classList.remove('visible');
        distBlue.classList.remove('visible');
        distFront.classList.add('visible');
      }
    }

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

    marks.forEach(mark => {
      mark.addEventListener('click', () => {
        showDistances(mark.dataset.target);
      });
    });

    showDistances('all');
  </script>
</body>
</html>

UK-GCSE-SCIENCE-CHEM-CA-01-05

Aligned learning resources

Related diagrams