<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Paper Chromatography Setups</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      user-select: none;
    }

    body {
      width: 100%;
      background: #ffffff;
      color: #0f172a;
      padding: 10px 8px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-start;
      gap: 8px;
    }

    .header-bar {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 10px;
      width: 100%;
      max-width: 660px;
    }

    .controls {
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .btn {
      background: #f8fafc;
      border: 1.5px solid #cbd5e1;
      color: #0f172a;
      padding: 6px 14px;
      border-radius: 6px;
      font-size: 13px;
      font-weight: 700;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      transition: background 0.15s, border-color 0.15s;
    }

    .btn:hover {
      background: #e2e8f0;
      border-color: #94a3b8;
    }

    .btn:active {
      background: #cbd5e1;
    }

    .btn-primary {
      background: #0284c7;
      border-color: #0284c7;
      color: #ffffff;
    }

    .btn-primary:hover {
      background: #0369a1;
      border-color: #0369a1;
    }

    .setups-grid {
      width: 100%;
      max-width: 660px;
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 8px;
    }

    .setup-card {
      background: #f8fafc;
      border: 1.5px solid #e2e8f0;
      border-radius: 8px;
      padding: 8px 4px 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      position: relative;
    }

    .setup-card.card-valid {
      border-color: #86efac;
      background: #fcfdfc;
    }

    .setup-card.card-invalid {
      border-color: #fca5a5;
      background: #fffdfd;
    }

    .card-info {
      display: flex;
      flex-direction: column;
      align-items: center;
      width: 100%;
    }

    .badge {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 4px;
      font-size: 11px;
      font-weight: 800;
      padding: 3px 10px;
      border-radius: 12px;
      margin-bottom: 6px;
      text-transform: uppercase;
      letter-spacing: 0.3px;
    }

    .badge-valid {
      background: #dcfce7;
      color: #15803d;
      border: 1px solid #86efac;
    }

    .badge-invalid {
      background: #fee2e2;
      color: #b91c1c;
      border: 1px solid #fca5a5;
    }

    .beaker-svg {
      width: 100%;
      max-width: 180px;
      height: auto;
      display: block;
      overflow: visible;
    }

    .tag-label {
      font-size: 12px;
      font-weight: 700;
      text-align: center;
      margin-top: 6px;
      line-height: 1.25;
    }

    .tag-label.highlight-err {
      color: #b91c1c;
    }

    .tag-label.highlight-ok {
      color: #15803d;
    }

    .svg-text {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      font-weight: 700;
    }

    /* Responsive Mobile Layout: Stacks horizontally per card for clean readability without squishing */
    @media (max-width: 540px) {
      body {
        padding: 6px 6px;
        gap: 6px;
      }
      .setups-grid {
        grid-template-columns: 1fr;
        gap: 6px;
      }
      .setup-card {
        flex-direction: row;
        align-items: center;
        justify-content: flex-start;
        padding: 6px 12px;
        gap: 12px;
      }
      .beaker-svg {
        width: 110px;
        max-width: 110px;
        flex-shrink: 0;
      }
      .card-info {
        align-items: flex-start;
        justify-content: center;
        flex: 1;
      }
      .badge {
        margin-bottom: 4px;
      }
      .tag-label {
        text-align: left;
        font-size: 12.5px;
        margin-top: 2px;
      }
    }
  </style>
</head>
<body>

  <div class="header-bar">
    <div class="controls">
      <button class="btn btn-primary" id="playBtn">▶ Run Experiment</button>
      <button class="btn" id="resetBtn">↺ Reset</button>
    </div>
  </div>

  <div class="setups-grid">
    
    <div class="setup-card card-valid">
      <div class="card-info" style="display: contents;">
        <svg class="beaker-svg" viewBox="0 0 175 200" aria-label="Correct chromatography setup">
          
          <rect x="28" y="22" width="118" height="170" rx="6" fill="#f0f9ff" fill-opacity="0.35" stroke="#64748b" stroke-width="2.5"/>
          <line x1="22" y1="22" x2="152" y2="22" stroke="#64748b" stroke-width="3" stroke-linecap="round"/>
          
          
          <path d="M 29 162 Q 87 160 145 162 L 145 188 Q 145 191 142 191 L 32 191 Q 29 191 29 188 Z" fill="#bae6fd" opacity="0.85"/>
          <line x1="29" y1="162" x2="145" y2="162" stroke="#0284c7" stroke-width="2"/>

          
          <rect x="60" y="28" width="54" height="152" fill="#ffffff" stroke="#94a3b8" stroke-width="1.5" rx="1"/>

          
          <rect id="solventFront1" x="61" y="162" width="52" height="0" fill="#bae6fd" opacity="0.55"/>

          
          <line x1="63" y1="142" x2="111" y2="142" stroke="#334155" stroke-width="1.75" stroke-dasharray="3 1.5"/>

          
          <circle id="spotYellow" cx="87" cy="142" r="4.5" fill="#ca8a04"/>
          <circle id="spotPink" cx="87" cy="142" r="4.5" fill="#db2777"/>
          <circle id="spotBlue" cx="87" cy="142" r="4.5" fill="#2563eb"/>
          
          <circle id="spotOriginal1" cx="87" cy="142" r="5" fill="#0f172a"/>

          
          <text class="svg-text" x="117" y="140" font-size="10" fill="#1e293b">Pencil line</text>
          <line x1="111" y1="142" x2="116" y2="140" stroke="#1e293b" stroke-width="1.25"/>

          
          <text class="svg-text" x="26" y="174" text-anchor="end" font-size="10" fill="#0369a1">Solvent</text>
          <line x1="27" y1="171" x2="33" y2="166" stroke="#0369a1" stroke-width="1.25"/>
        </svg>

        <div class="card-info">
          <div class="badge badge-valid">✓ Correct</div>
          <div class="tag-label highlight-ok">Solvent below<br>pencil baseline</div>
        </div>
      </div>
    </div>

    
    <div class="setup-card card-invalid">
      <div class="card-info" style="display: contents;">
        <svg class="beaker-svg" viewBox="0 0 175 200" aria-label="Incorrect setup with pen baseline">
          
          <rect x="28" y="22" width="118" height="170" rx="6" fill="#f0f9ff" fill-opacity="0.35" stroke="#64748b" stroke-width="2.5"/>
          <line x1="22" y1="22" x2="152" y2="22" stroke="#64748b" stroke-width="3" stroke-linecap="round"/>
          
          
          <path d="M 29 162 Q 87 160 145 162 L 145 188 Q 145 191 142 191 L 32 191 Q 29 191 29 188 Z" fill="#bae6fd" opacity="0.85"/>
          <line x1="29" y1="162" x2="145" y2="162" stroke="#0284c7" stroke-width="2"/>

          
          <rect x="60" y="28" width="54" height="152" fill="#ffffff" stroke="#94a3b8" stroke-width="1.5" rx="1"/>

          
          <rect id="solventFront2" x="61" y="162" width="52" height="0" fill="#bae6fd" opacity="0.55"/>

          
          <rect id="penSmear" x="63" y="140" width="48" height="3" fill="#4f46e5" opacity="0" rx="2"/>

          
          <line id="penLine" x1="63" y1="142" x2="111" y2="142" stroke="#4338ca" stroke-width="2.5"/>

          
          <circle id="spot2" cx="87" cy="142" r="5" fill="#0f172a"/>

          
          <text class="svg-text" x="117" y="140" font-size="10" fill="#b91c1c">Pen ink!</text>
          <line x1="111" y1="142" x2="116" y2="140" stroke="#b91c1c" stroke-width="1.25"/>
        </svg>

        <div class="card-info">
          <div class="badge badge-invalid">✗ Wrong</div>
          <div class="tag-label highlight-err">Pen ink blurs<br>into sample</div>
        </div>
      </div>
    </div>

    
    <div class="setup-card card-invalid">
      <div class="card-info" style="display: contents;">
        <svg class="beaker-svg" viewBox="0 0 175 200" aria-label="Incorrect setup with deep solvent">
          
          <rect x="28" y="22" width="118" height="170" rx="6" fill="#f0f9ff" fill-opacity="0.35" stroke="#64748b" stroke-width="2.5"/>
          <line x1="22" y1="22" x2="152" y2="22" stroke="#64748b" stroke-width="3" stroke-linecap="round"/>
          
          
          <path d="M 29 125 Q 87 123 145 125 L 145 188 Q 145 191 142 191 L 32 191 Q 29 191 29 188 Z" fill="#bae6fd" opacity="0.85"/>
          <line x1="29" y1="125" x2="145" y2="125" stroke="#0284c7" stroke-width="2"/>

          
          <rect x="60" y="28" width="54" height="152" fill="#ffffff" stroke="#94a3b8" stroke-width="1.5" rx="1"/>

          
          <line x1="63" y1="142" x2="111" y2="142" stroke="#334155" stroke-width="1.75" stroke-dasharray="3 1.5"/>

          
          <ellipse id="dissolveCloud1" cx="87" cy="155" rx="4" ry="3" fill="#4f46e5" opacity="0"/>
          <ellipse id="dissolveCloud2" cx="87" cy="168" rx="8" ry="5" fill="#2563eb" opacity="0"/>
          <ellipse id="dissolveCloud3" cx="87" cy="178" rx="14" ry="7" fill="#db2777" opacity="0"/>

          
          <circle id="spot3" cx="87" cy="142" r="5" fill="#0f172a"/>

          
          <text class="svg-text" x="26" y="126" text-anchor="end" font-size="10" fill="#b91c1c">Too deep!</text>
          <line x1="27" y1="125" x2="33" y2="125" stroke="#b91c1c" stroke-width="1.25"/>
        </svg>

        <div class="card-info">
          <div class="badge badge-invalid">✗ Wrong</div>
          <div class="tag-label highlight-err">Sample washes<br>into solvent pool</div>
        </div>
      </div>
    </div>
  </div>

  <script>
    const playBtn = document.getElementById('playBtn');
    const resetBtn = document.getElementById('resetBtn');

    // DOM Elements
    const solventFront1 = document.getElementById('solventFront1');
    const solventFront2 = document.getElementById('solventFront2');
    const spotOriginal1 = document.getElementById('spotOriginal1');
    const spotYellow = document.getElementById('spotYellow');
    const spotPink = document.getElementById('spotPink');
    const spotBlue = document.getElementById('spotBlue');
    const penSmear = document.getElementById('penSmear');
    const spot2 = document.getElementById('spot2');
    const spot3 = document.getElementById('spot3');
    const dissolveCloud1 = document.getElementById('dissolveCloud1');
    const dissolveCloud2 = document.getElementById('dissolveCloud2');
    const dissolveCloud3 = document.getElementById('dissolveCloud3');

    const DURATION = 3000; // ms
    let progress = 0; // 0 to 1
    let isPlaying = false;
    let animFrameId = null;
    let lastTimestamp = null;

    function easeOut(t) {
      return 1 - Math.pow(1 - t, 2.2);
    }

    function lerp(start, end, t) {
      return start + (end - start) * Math.max(0, Math.min(1, t));
    }

    function subProgress(p, startProg, endProg) {
      if (p <= startProg) return 0;
      if (p >= endProg) return 1;
      const t = (p - startProg) / (endProg - startProg);
      return easeOut(t);
    }

    function render(p) {
      // 1. Solvent Fronts (y: 162 -> 48, height: 0 -> 114)
      const sfP = subProgress(p, 0.0, 1.0);
      const sfY = lerp(162, 48, sfP);
      const sfH = lerp(0, 114, sfP);
      solventFront1.setAttribute('y', sfY);
      solventFront1.setAttribute('height', sfH);
      solventFront2.setAttribute('y', sfY);
      solventFront2.setAttribute('height', sfH);

      // 2. Setup 1: Original spot fades, 3 component spots travel up
      const s1OrigP = subProgress(p, 0.0, 0.25);
      spotOriginal1.style.opacity = lerp(1, 0, s1OrigP);

      const s1TravelP = subProgress(p, 0.05, 1.0);
      spotYellow.setAttribute('cy', lerp(142, 62, s1TravelP));
      spotPink.setAttribute('cy', lerp(142, 88, s1TravelP));
      spotBlue.setAttribute('cy', lerp(142, 114, s1TravelP));

      // 3. Setup 2: Pen line smearing upward, contaminating sample
      const s2P = subProgress(p, 0.05, 1.0);
      const smearY = lerp(140, 65, s2P);
      const smearH = lerp(3, 77, s2P);
      const smearOp = lerp(0, 0.72, s2P);
      penSmear.setAttribute('y', smearY);
      penSmear.setAttribute('height', smearH);
      penSmear.style.opacity = smearOp;

      const spot2P = subProgress(p, 0.05, 1.0);
      spot2.setAttribute('cy', lerp(142, 85, spot2P));
      spot2.style.opacity = lerp(1, 0.35, spot2P);

      // 4. Setup 3: Submerged spot dissolves downward into liquid pool
      const s3FadeP = subProgress(p, 0.0, 0.5);
      spot3.setAttribute('r', lerp(5, 2, s3FadeP));
      spot3.style.opacity = lerp(1, 0.12, s3FadeP);

      const c1P = subProgress(p, 0.05, 0.55);
      dissolveCloud1.setAttribute('rx', lerp(4, 20, c1P));
      dissolveCloud1.setAttribute('ry', lerp(3, 8, c1P));
      dissolveCloud1.style.opacity = lerp(0, 0.65, c1P);

      const c2P = subProgress(p, 0.15, 0.75);
      dissolveCloud2.setAttribute('rx', lerp(8, 32, c2P));
      dissolveCloud2.setAttribute('ry', lerp(5, 11, c2P));
      dissolveCloud2.style.opacity = lerp(0, 0.55, c2P);

      const c3P = subProgress(p, 0.25, 0.95);
      dissolveCloud3.setAttribute('rx', lerp(14, 42, c3P));
      dissolveCloud3.setAttribute('ry', lerp(7, 13, c3P));
      dissolveCloud3.style.opacity = lerp(0, 0.45, c3P);
    }

    function animate(timestamp) {
      if (!lastTimestamp) lastTimestamp = timestamp;
      const delta = timestamp - lastTimestamp;
      lastTimestamp = timestamp;

      progress += delta / DURATION;
      if (progress >= 1) {
        progress = 1;
        isPlaying = false;
        playBtn.innerHTML = '↺ Replay';
        render(1);
        return;
      }

      render(progress);

      if (isPlaying) {
        animFrameId = requestAnimationFrame(animate);
      }
    }

    function play() {
      if (progress >= 1) {
        progress = 0;
      }
      isPlaying = true;
      lastTimestamp = null;
      playBtn.innerHTML = '⏸ Pause';
      animFrameId = requestAnimationFrame(animate);
    }

    function pause() {
      isPlaying = false;
      if (animFrameId) cancelAnimationFrame(animFrameId);
      playBtn.innerHTML = '▶ Run';
    }

    function reset() {
      pause();
      progress = 0;
      render(0);
      playBtn.innerHTML = '▶ Run';
    }

    playBtn.addEventListener('click', () => {
      if (isPlaying) {
        pause();
      } else {
        play();
      }
    });

    resetBtn.addEventListener('click', reset);

    // Baseline state render
    render(0);

    // Auto-run on start
    setTimeout(() => {
      play();
    }, 400);
  </script>
</body>
</html>

Introduction to Chromatography and Phase Definitions

<!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;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
      padding: 12px 8px;
    }

    .diagram-area {
      display: flex;
      justify-content: center;
      align-items: flex-end;
      gap: 28px;
      width: 100%;
      max-width: 480px;
      height: 310px;
      position: relative;
    }

    .strip-col {
      display: flex;
      flex-direction: column;
      align-items: center;
      flex: 1;
      max-width: 170px;
      height: 100%;
    }

    .strip-title {
      font-size: 14px;
      font-weight: 700;
      color: #475569;
      margin-bottom: 8px;
      text-transform: uppercase;
      letter-spacing: 0.5px;
    }

    .strip-container {
      position: relative;
      width: 100%;
      height: 270px;
      background: #f8fafc;
      border: 2px solid #cbd5e1;
      border-radius: 6px;
      overflow: hidden;
    }

    /* Baseline pencil line */
    .pencil-line {
      position: absolute;
      bottom: 40px;
      left: 12px;
      right: 12px;
      height: 1px;
      border-bottom: 1.5px dashed #94a3b8;
    }

    /* Solvent bath */
    .solvent-bath {
      position: absolute;
      bottom: 0;
      left: 0;
      right: 0;
      height: 22px;
      background: rgba(34, 183, 255, 0.2);
      border-top: 1px solid rgba(34, 183, 255, 0.4);
    }

    /* Solvent Front in active strip */
    .solvent-front {
      position: absolute;
      bottom: 40px;
      left: 0;
      right: 0;
      height: 0%;
      background: rgba(34, 183, 255, 0.15);
      border-top: 2px dashed #0284c7;
      transition: height 3.2s cubic-bezier(0.2, 0.8, 0.25, 1);
    }

    .solvent-label {
      position: absolute;
      top: -18px;
      right: 6px;
      font-size: 11px;
      font-weight: 600;
      color: #0284c7;
      opacity: 0;
      transition: opacity 0.4s ease 3s;
      white-space: nowrap;
    }

    /* Spots */
    .spot {
      position: absolute;
      left: 50%;
      transform: translate(-50%, 50%);
      border-radius: 50%;
      box-shadow: 0 1px 3px rgba(0,0,0,0.25);
      transition: all 3.2s cubic-bezier(0.2, 0.8, 0.25, 1);
    }

    .spot-black {
      bottom: 40px;
      width: 18px;
      height: 18px;
      background: #0f172a;
    }

    .spot-blue {
      bottom: 40px;
      width: 16px;
      height: 16px;
      background: #2563eb;
      opacity: 0;
    }

    .spot-magenta {
      bottom: 40px;
      width: 16px;
      height: 16px;
      background: #ec4899;
      opacity: 0;
    }

    .spot-yellow {
      bottom: 40px;
      width: 16px;
      height: 16px;
      background: #eab308;
      opacity: 0;
    }

    /* Spot Labels */
    .spot-tag {
      position: absolute;
      left: 68%;
      font-size: 12px;
      font-weight: 700;
      white-space: nowrap;
      transform: translateY(50%);
      opacity: 0;
      transition: opacity 0.4s ease 3.2s;
    }

    .tag-black { bottom: 40px; color: #0f172a; opacity: 1; }
    .tag-blue { bottom: 220px; color: #1d4ed8; }
    .tag-magenta { bottom: 155px; color: #db2777; }
    .tag-yellow { bottom: 95px; color: #ca8a04; }

    /* Animated active states */
    .running .solvent-front {
      height: 200px;
    }
    .running .solvent-label {
      opacity: 1;
    }
    .running .spot-origin-fade {
      opacity: 0.15;
      transform: translate(-50%, 50%) scale(0.6);
    }
    .running .spot-blue {
      bottom: 220px;
      opacity: 0.95;
    }
    .running .spot-magenta {
      bottom: 155px;
      opacity: 0.95;
    }
    .running .spot-yellow {
      bottom: 95px;
      opacity: 0.95;
    }
    .running .spot-tag {
      opacity: 1;
    }

    /* Controls */
    .controls {
      margin-top: 12px;
      display: flex;
      justify-content: center;
      gap: 12px;
    }

    .btn {
      background: #0284c7;
      color: #ffffff;
      border: none;
      padding: 9px 20px;
      font-size: 14px;
      font-weight: 600;
      border-radius: 8px;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 6px;
      box-shadow: 0 2px 4px rgba(2, 132, 199, 0.3);
    }
    .btn:active {
      background: #0369a1;
      transform: translateY(1px);
    }
  </style>
</head>
<body>

  <div class="diagram-area">
    
    <div class="strip-col">
      <div class="strip-title">Before</div>
      <div class="strip-container">
        <div class="pencil-line"></div>
        <div class="solvent-bath"></div>
        <div class="spot spot-black"></div>
        <div class="spot-tag tag-black">Black Ink</div>
      </div>
    </div>

    
    <div class="strip-col" id="devColumn">
      <div class="strip-title">After</div>
      <div class="strip-container" id="devStrip">
        <div class="solvent-front">
          <span class="solvent-label">Solvent Front</span>
        </div>
        <div class="pencil-line"></div>
        <div class="solvent-bath"></div>

        <div class="spot spot-black spot-origin-fade"></div>
        <div class="spot spot-yellow"></div>
        <div class="spot spot-magenta"></div>
        <div class="spot spot-blue"></div>

        <div class="spot-tag tag-blue">Blue</div>
        <div class="spot-tag tag-magenta">Magenta</div>
        <div class="spot-tag tag-yellow">Yellow</div>
      </div>
    </div>
  </div>

  <div class="controls">
    <button class="btn" id="actionBtn" onclick="toggleSeparation()">
      <span>▶ Run Separation</span>
    </button>
  </div>

  <script>
    let isRunning = false;
    const devColumn = document.getElementById('devColumn');
    const actionBtn = document.getElementById('actionBtn');

    function toggleSeparation() {
      isRunning = !isRunning;
      if (isRunning) {
        devColumn.classList.add('running');
        actionBtn.innerHTML = '<span>↺ Reset</span>';
      } else {
        devColumn.classList.remove('running');
        actionBtn.innerHTML = '<span>▶ Run Separation</span>';
      }
    }
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="1:1">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      background: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100vh;
      padding: 8px;
      user-select: none;
    }
    .diagram-wrap {
      position: relative;
      width: 100%;
      max-width: 480px;
      aspect-ratio: 1 / 1;
      display: flex;
      flex-direction: column;
      align-items: center;
    }
    svg {
      width: 100%;
      height: 100%;
      overflow: visible;
    }
    /* Label typography */
    .lbl-title {
      font-size: 11.5px;
      font-weight: 700;
      fill: #1e2945;
    }
    .lbl-sub {
      font-size: 10px;
      font-weight: 500;
      fill: #64748b;
    }
    .pointer-line {
      stroke: #94a3b8;
      stroke-width: 1.25;
      stroke-dasharray: 2 2;
      fill: none;
    }
    .pointer-dot {
      fill: #3b82f6;
    }
    /* Animated flow arrows */
    @keyframes climbArrow {
      0% { transform: translateY(0); opacity: 0; }
      20% { opacity: 0.8; }
      80% { opacity: 0.8; }
      100% { transform: translateY(-42px); opacity: 0; }
    }
    .flow-arrow {
      animation: climbArrow 2.4s ease-in-out infinite;
      fill: #0284c7;
    }
    .flow-arrow.delay-1 { animation-delay: 0.8s; }
    .flow-arrow.delay-2 { animation-delay: 1.6s; }

    /* Controls bar */
    .controls {
      position: absolute;
      bottom: 6px;
      display: flex;
      gap: 8px;
      align-items: center;
      background: rgba(248, 250, 252, 0.95);
      border: 1px solid #e2e8f0;
      border-radius: 20px;
      padding: 4px 10px;
      box-shadow: 0 2px 6px rgba(0,0,0,0.05);
    }
    .btn {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 12px;
      padding: 3px 10px;
      font-size: 11px;
      font-weight: 600;
      color: #334155;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 4px;
      transition: background 0.15s, border-color 0.15s;
    }
    .btn:active {
      background: #f1f5f9;
    }
    .btn.active {
      background: #eff6ff;
      border-color: #3b82f6;
      color: #1d4ed8;
    }
  </style>
</head>
<body>
  <div class="diagram-wrap">
    <svg viewBox="0 0 500 500" aria-label="Paper Chromatography Apparatus Diagram">
      <defs>
        
        <linearGradient id="solventGrad" x1="0" y1="0" x2="0" y2="1">
          <stop offset="0%" stop-color="#bae6fd" stop-opacity="0.6"/>
          <stop offset="100%" stop-color="#38bdf8" stop-opacity="0.85"/>
        </linearGradient>
        
        <linearGradient id="glassGrad" x1="0" y1="0" x2="1" y2="0">
          <stop offset="0%" stop-color="#ffffff" stop-opacity="0.5"/>
          <stop offset="8%" stop-color="#e0f2fe" stop-opacity="0.2"/>
          <stop offset="92%" stop-color="#e0f2fe" stop-opacity="0.2"/>
          <stop offset="100%" stop-color="#bae6fd" stop-opacity="0.4"/>
        </linearGradient>
        
        <linearGradient id="wetPaperGrad" x1="0" y1="1" x2="0" y2="0">
          <stop offset="0%" stop-color="#dbeafe"/>
          <stop offset="100%" stop-color="#f8fafc"/>
        </linearGradient>
        
        <filter id="softShadow" x="-5%" y="-5%" width="110%" height="110%">
          <feDropShadow dx="0" dy="2" stdDeviation="3" flood-opacity="0.08"/>
        </filter>
        
        <marker id="arrowUp" viewBox="0 0 6 6" refX="3" refY="3" markerWidth="4" markerHeight="4" orient="auto">
          <path d="M 3 0 L 6 6 L 0 6 Z" fill="#0284c7"/>
        </marker>
      </defs>

      
      
      <ellipse cx="250" cy="110" rx="100" ry="14" fill="#e2e8f0" stroke="#cbd5e1" stroke-width="1.5"/>

      
      
      <g filter="url(#softShadow)">
        <rect x="220" y="85" width="60" height="340" rx="2" fill="#ffffff" stroke="#cbd5e1" stroke-width="1.5"/>
      </g>

      
      <rect id="wetPaper" x="221" y="210" width="58" height="214" fill="url(#wetPaperGrad)" opacity="0.8"/>

      
      <g id="solventFrontGroup">
        <line id="solventFrontLine" x1="220" y1="210" x2="280" y2="210" stroke="#0284c7" stroke-width="2.5" stroke-dasharray="3 2"/>
      </g>

      
      <g id="pigmentSpots">
        
        <ellipse id="spotYellow" cx="250" cy="235" rx="6" ry="4.5" fill="#eab308" opacity="0.9"/>
        
        <ellipse id="spotPink" cx="250" cy="285" rx="5.5" ry="4" fill="#ec4899" opacity="0.9"/>
        
        <ellipse id="spotBlue" cx="250" cy="335" rx="5" ry="3.5" fill="#3b82f6" opacity="0.9"/>
      </g>

      
      <line x1="220" y1="385" x2="280" y2="385" stroke="#64748b" stroke-width="1.5"/>
      
      <circle cx="250" cy="385" r="3" fill="#334155"/>

      
      <g id="flowArrowsGroup" opacity="0.9">
        <path class="flow-arrow" d="M 235 370 L 235 345" stroke="#0284c7" stroke-width="2" marker-end="url(#arrowUp)"/>
        <path class="flow-arrow delay-1" d="M 265 370 L 265 345" stroke="#0284c7" stroke-width="2" marker-end="url(#arrowUp)"/>
        <path class="flow-arrow delay-2" d="M 250 315 L 250 290" stroke="#0284c7" stroke-width="2" marker-end="url(#arrowUp)"/>
      </g>

      
      
      <path d="M 152 400 Q 250 412 348 400 L 348 430 Q 348 450 325 450 L 175 450 Q 152 450 152 430 Z" fill="url(#solventGrad)"/>
      
      <ellipse cx="250" cy="400" rx="98" ry="12" fill="#7dd3fc" stroke="#38bdf8" stroke-width="1" opacity="0.85"/>
      <ellipse cx="250" cy="400" rx="96" ry="10" fill="#bae6fd" opacity="0.6"/>

      
      <path d="M 150 110 L 150 430 A 25 25 0 0 0 175 455 L 325 455 A 25 25 0 0 0 350 430 L 350 110" 
            fill="url(#glassGrad)" stroke="#94a3b8" stroke-width="2.5" stroke-linejoin="round"/>
      
      <path d="M 146 110 Q 250 126 354 110" fill="none" stroke="#94a3b8" stroke-width="2.5"/>

      
      <path d="M 136 102 Q 250 82 364 102 L 360 108 Q 250 90 140 108 Z" fill="#e0f2fe" stroke="#64748b" stroke-width="1.8" opacity="0.95"/>
      <ellipse cx="250" cy="100" rx="114" ry="10" fill="#f8fafc" stroke="#94a3b8" stroke-width="1.5" opacity="0.7"/>

      
      <rect x="238" y="76" width="24" height="14" rx="2" fill="#475569" stroke="#1e2945" stroke-width="1"/>
      <circle cx="250" cy="83" r="2.5" fill="#f8fafc"/>

      

      
      <g id="lblSolventFront">
        <text x="340" y="195" class="lbl-title">Solvent Front</text>
        <text x="340" y="209" class="lbl-sub">(Leading Edge)</text>
        <polyline class="pointer-line" points="334,203 295,203 282,210"/>
        <circle cx="282" cy="210" r="3" class="pointer-dot"/>
      </g>

      
      <g id="lblStationary">
        <text x="160" y="145" text-anchor="end" class="lbl-title">Stationary Phase</text>
        <text x="160" y="159" text-anchor="end" class="lbl-sub">(Chromatography Paper)</text>
        <polyline class="pointer-line" points="166,152 205,152 220,160"/>
        <circle cx="220" cy="160" r="3" class="pointer-dot"/>
      </g>

      
      <g id="lblBaseline">
        <text x="160" y="375" text-anchor="end" class="lbl-title">Baseline</text>
        <text x="160" y="389" text-anchor="end" class="lbl-sub">(Pencil Line)</text>
        <polyline class="pointer-line" points="166,382 205,382 218,385"/>
        <circle cx="218" cy="385" r="3" class="pointer-dot"/>
      </g>

      
      <g id="lblMobile">
        <text x="340" y="420" class="lbl-title">Mobile Phase</text>
        <text x="340" y="434" class="lbl-sub">(Solvent)</text>
        <polyline class="pointer-line" points="334,427 305,427 285,418"/>
        <circle cx="285" cy="418" r="3" class="pointer-dot"/>
      </g>

      
      <text x="250" y="468" text-anchor="middle" font-size="9.5" font-weight="600" fill="#64748b">Solvent level below pencil baseline</text>
    </svg>

    
    <div class="controls">
      <button id="btnPlay" class="btn active" title="Toggle climb animation">
        <span id="playIcon">⏸</span> Pause
      </button>
      <button id="btnReset" class="btn" title="Reset run">
        ↺ Restart
      </button>
    </div>
  </div>

  <script>
    let isPlaying = true;
    let animProgress = 1.0; // 0 = start at baseline, 1 = fully developed
    let animDirection = 1;
    let lastTime = null;

    const wetPaper = document.getElementById('wetPaper');
    const solventFrontLine = document.getElementById('solventFrontLine');
    const spotYellow = document.getElementById('spotYellow');
    const spotPink = document.getElementById('spotPink');
    const spotBlue = document.getElementById('spotBlue');
    const flowArrows = document.getElementById('flowArrowsGroup');
    const btnPlay = document.getElementById('btnPlay');
    const btnReset = document.getElementById('btnReset');
    const playIcon = document.getElementById('playIcon');
    const lblFront = document.getElementById('lblSolventFront');

    const BASELINE_Y = 385;
    const FRONT_END_Y = 210;
    const PAPER_BOTTOM_Y = 424;

    function setChromatographyProgress(p) {
      // p ranges from 0 to 1
      const currentFrontY = BASELINE_Y - p * (BASELINE_Y - FRONT_END_Y);
      
      // Update wet paper
      wetPaper.setAttribute('y', currentFrontY);
      wetPaper.setAttribute('height', PAPER_BOTTOM_Y - currentFrontY);
      
      // Update solvent front line
      solventFrontLine.setAttribute('y1', currentFrontY);
      solventFrontLine.setAttribute('y2', currentFrontY);

      // Update spot positions proportionally based on Rf values
      // Yellow: Rf ~ 0.85
      const yellowY = BASELINE_Y - (BASELINE_Y - currentFrontY) * 0.86;
      spotYellow.setAttribute('cy', yellowY);
      spotYellow.setAttribute('opacity', p > 0.05 ? 0.9 : p * 18);

      // Pink: Rf ~ 0.57
      const pinkY = BASELINE_Y - (BASELINE_Y - currentFrontY) * 0.57;
      spotPink.setAttribute('cy', pinkY);
      spotPink.setAttribute('opacity', p > 0.05 ? 0.9 : p * 18);

      // Blue: Rf ~ 0.28
      const blueY = BASELINE_Y - (BASELINE_Y - currentFrontY) * 0.28;
      spotBlue.setAttribute('cy', blueY);
      spotBlue.setAttribute('opacity', p > 0.05 ? 0.9 : p * 18);

      // Update pointer line for Solvent Front
      const poly = lblFront.querySelector('polyline');
      const dot = lblFront.querySelector('.pointer-dot');
      poly.setAttribute('points', `334,203 295,${Math.min(203, currentFrontY)} 282,${currentFrontY}`);
      dot.setAttribute('cy', currentFrontY);
    }

    function animate(time) {
      if (!lastTime) lastTime = time;
      const dt = (time - lastTime) / 1000;
      lastTime = time;

      if (isPlaying) {
        // Slow pedagogical progression (~6s full climb, 2s pause at peak)
        animProgress += dt * 0.22;
        if (animProgress > 1.35) {
          // Reset atomically after calm pause
          animProgress = 0;
        }
        const effectiveP = Math.min(1, animProgress);
        setChromatographyProgress(effectiveP);
      }

      requestAnimationFrame(animate);
    }

    requestAnimationFrame(animate);

    btnPlay.addEventListener('click', () => {
      isPlaying = !isPlaying;
      btnPlay.classList.toggle('active', isPlaying);
      playIcon.textContent = isPlaying ? '⏸' : '▶';
      btnPlay.innerHTML = `<span id="playIcon">${isPlaying ? '⏸' : '▶'}</span> ${isPlaying ? 'Pause' : 'Play'}`;
      flowArrows.style.display = isPlaying ? 'block' : 'none';
    });

    btnReset.addEventListener('click', () => {
      animProgress = 0;
      setChromatographyProgress(0);
    });
  </script>
</body>
</html>

UK-GCSE-SCIENCE-CHEM-CA-01-04

Aligned learning resources

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