<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: transparent;
      color: #0f172a;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-start;
      width: 100%;
      min-height: 100%;
      padding: 8px 4px;
      overflow-x: hidden;
      user-select: none;
    }

    .controls {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      margin-bottom: 10px;
      width: 100%;
      max-width: 520px;
      flex-wrap: wrap;
    }

    .step-btn {
      background: #f8fafc;
      border: 1.5px solid #cbd5e1;
      border-radius: 20px;
      padding: 6px 12px;
      font-size: 12px;
      font-weight: 700;
      color: #334155;
      cursor: pointer;
      transition: background-color 0.3s ease, border-color 0.3s ease, color 0.3s ease;
    }
    .step-btn:hover {
      background: #f1f5f9;
      border-color: #94a3b8;
    }
    .step-btn.active {
      background: #0284c7;
      border-color: #0284c7;
      color: #ffffff;
    }

    .play-btn {
      background: #f8fafc;
      border: 1.5px solid #cbd5e1;
      border-radius: 50%;
      width: 32px;
      height: 32px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 13px;
      cursor: pointer;
      color: #0f172a;
      transition: background-color 0.3s ease, border-color 0.3s ease;
    }
    .play-btn:hover {
      background: #f1f5f9;
      border-color: #94a3b8;
    }

    .diagram-svg {
      width: 100%;
      max-width: 520px;
      height: auto;
      display: block;
    }

    /* SVG text styling */
    .txt-boundary { font-size: 13px; font-weight: 800; fill: #ffffff; letter-spacing: 0.6px; }
    .txt-zone-sub { font-size: 11px; font-weight: 700; fill: #0369a1; letter-spacing: 0.4px; }
    .txt-atom { font-size: 13px; font-weight: 800; fill: #ffffff; text-anchor: middle; dominant-baseline: central; }
    .txt-title { font-size: 12px; font-weight: 800; fill: #0f172a; text-anchor: middle; }
    .txt-label-main { font-size: 12px; font-weight: 700; fill: #b91c1c; text-anchor: middle; }
    .txt-label-sub { font-size: 10.5px; font-weight: 600; fill: #475569; text-anchor: middle; }

    /* Molecule Vibrations - Smooth transitions >= 300ms */
    @keyframes co2-vibrate {
      0%, 100% { transform: translate(0, 0) rotate(0deg); }
      25% { transform: translate(-2px, -1.5px) rotate(-1.5deg); }
      50% { transform: translate(2px, 1.5px) rotate(1.5deg); }
      75% { transform: translate(-1.5px, 1.5px) rotate(-1deg); }
    }
    @keyframes spring-l-motion {
      0%, 100% { transform: scaleX(1); }
      50% { transform: scaleX(0.82); }
    }
    @keyframes spring-r-motion {
      0%, 100% { transform: scaleX(1); }
      50% { transform: scaleX(1.18); }
    }

    .vibrating {
      animation: co2-vibrate 0.45s infinite ease-in-out;
      transform-origin: 260px 185px;
    }
    .vibrating #spring-l {
      animation: spring-l-motion 0.45s infinite ease-in-out;
      transform-origin: 260px 185px;
    }
    .vibrating #spring-r {
      animation: spring-r-motion 0.45s infinite ease-in-out;
      transform-origin: 260px 185px;
    }

    /* Wave Transitions */
    .ir-wave {
      transition: opacity 0.4s ease, transform 0.4s ease;
    }

    .step-desc-box {
      font-size: 12px;
      font-weight: 600;
      fill: #1e293b;
      text-anchor: middle;
    }
  </style>
</head>
<body>

  
  <div class="controls">
    <button id="playBtn" class="play-btn" aria-label="Play/Pause">⏸</button>
    <button class="step-btn active" onclick="setStep(0)">1. IR Photon Emitted</button>
    <button class="step-btn" onclick="setStep(1)">2. Absorption &amp; Vibration</button>
    <button class="step-btn" onclick="setStep(2)">3. Greenhouse Re-radiation</button>
  </div>

  <svg class="diagram-svg" viewBox="0 0 520 375" aria-label="Greenhouse Gas Molecular Absorption and Re-radiation Diagram">
    <defs>
      
      <linearGradient id="spaceGrad" x1="0" y1="0" x2="0" y2="1">
        <stop offset="0%" stop-color="#020617"/>
        <stop offset="100%" stop-color="#0f172a"/>
      </linearGradient>
      <linearGradient id="earthGrad" x1="0" y1="0" x2="0" y2="1">
        <stop offset="0%" stop-color="#15803d"/>
        <stop offset="100%" stop-color="#14532d"/>
      </linearGradient>
      <linearGradient id="atmoGrad" x1="0" y1="0" x2="0" y2="1">
        <stop offset="0%" stop-color="#f0f9ff"/>
        <stop offset="100%" stop-color="#e0f2fe"/>
      </linearGradient>

      
      <filter id="glow" x="-20%" y="-20%" width="140%" height="140%">
        <feGaussianBlur stdDeviation="2.5" result="blur" />
        <feComposite in="SourceGraphic" in2="blur" operator="over" />
      </filter>
    </defs>

    
    
    <rect x="0" y="44" width="520" height="284" fill="url(#atmoGrad)" />
    <text x="16" y="64" class="txt-zone-sub">ATMOSPHERE (GREENHOUSE GASES)</text>

    
    <rect x="0" y="0" width="520" height="44" fill="url(#spaceGrad)" />
    <text x="16" y="27" class="txt-boundary">OUTER SPACE</text>
    <text x="504" y="27" font-size="15" text-anchor="end">🌌</text>

    
    <rect x="0" y="328" width="520" height="47" fill="url(#earthGrad)" />
    <text x="16" y="356" class="txt-boundary">EARTH'S SURFACE</text>
    <text x="504" y="357" font-size="15" text-anchor="end">🌍</text>

    
    <g id="h2o-mol" transform="translate(68, 115)">
      
      <circle cx="0" cy="0" r="14" fill="#ef4444" stroke="#b91c1c" stroke-width="2"/>
      <text x="0" y="1" class="txt-atom">O</text>
      
      <line x1="-8" y1="9" x2="-18" y2="20" stroke="#64748b" stroke-width="3" stroke-linecap="round"/>
      <line x1="8" y1="9" x2="18" y2="20" stroke="#64748b" stroke-width="3" stroke-linecap="round"/>
      
      <circle cx="-22" cy="24" r="8.5" fill="#475569" stroke="#334155" stroke-width="1.5"/>
      <text x="-22" y="25" font-size="9" class="txt-atom">H</text>
      <circle cx="22" cy="24" r="8.5" fill="#475569" stroke="#334155" stroke-width="1.5"/>
      <text x="22" y="25" font-size="9" class="txt-atom">H</text>
      <rect x="-26" y="40" width="52" height="18" rx="4" fill="#ffffff" fill-opacity="0.9" stroke="#cbd5e1" stroke-width="1"/>
      <text x="0" y="53" font-size="10" fill="#334155" font-weight="700" text-anchor="middle">H₂O</text>
    </g>

    
    <circle id="energy-halo" cx="260" cy="185" r="48" fill="none" stroke="#ef4444" stroke-width="2.5" stroke-dasharray="5,4" opacity="0"/>

    
    <g id="co2-molecule">
      
      <rect x="200" y="132" width="120" height="20" rx="10" fill="#ffffff" fill-opacity="0.95" stroke="#cbd5e1" stroke-width="1.5"/>
      <text x="260" y="146" class="txt-title">CO₂ Molecule</text>

      
      <path id="spring-l" d="M 178,185 Q 188,175 198,185 Q 208,195 218,185 Q 228,175 238,185" 
            fill="none" stroke="#64748b" stroke-width="3.5" stroke-linecap="round"/>
      
      <path id="spring-r" d="M 282,185 Q 292,175 302,185 Q 312,195 322,185 Q 332,175 342,185" 
            fill="none" stroke="#64748b" stroke-width="3.5" stroke-linecap="round"/>

      
      <circle cx="160" cy="185" r="18" fill="#ef4444" stroke="#b91c1c" stroke-width="2"/>
      <text x="160" y="185" class="txt-atom">O</text>

      
      <circle cx="260" cy="185" r="22" fill="#1e293b" stroke="#0f172a" stroke-width="2"/>
      <text x="260" y="185" class="txt-atom">C</text>

      
      <circle cx="360" cy="185" r="18" fill="#ef4444" stroke="#b91c1c" stroke-width="2"/>
      <text x="360" y="185" class="txt-atom">O</text>
    </g>

    
    <g id="incoming-ir" class="ir-wave" opacity="1">
      
      <path d="M 260,326 Q 246,300 260,278 Q 274,256 260,234 Q 252,224 260,214" 
            fill="none" stroke="#dc2626" stroke-width="3.5" stroke-linecap="round" filter="url(#glow)"/>
      <polygon points="260,207 253,220 267,220" fill="#dc2626"/>

      
      <rect x="282" y="260" width="165" height="34" rx="6" fill="#ffffff" stroke="#fca5a5" stroke-width="1.5"/>
      <text x="364" y="275" class="txt-label-main">Infrared photon (heat)</text>
      <text x="364" y="288" class="txt-label-sub">Emitted by Earth's surface</text>
    </g>

    
    <g id="vibrate-label" opacity="0" style="transition: opacity 0.4s ease;">
      <rect x="180" y="222" width="160" height="24" rx="6" fill="#fef2f2" stroke="#ef4444" stroke-width="1.5"/>
      <text x="260" y="238" font-size="11.5" font-weight="700" fill="#b91c1c" text-anchor="middle">Bonds Vibrate &amp; Bend</text>
    </g>

    
    
    <g id="rerad-space" class="ir-wave" opacity="0">
      <path d="M 260,126 Q 246,104 260,82 Q 274,62 260,48" 
            fill="none" stroke="#dc2626" stroke-width="3.5" stroke-linecap="round" filter="url(#glow)"/>
      <polygon points="260,42 253,54 267,54" fill="#dc2626"/>
      
      
      <rect x="282" y="66" width="160" height="34" rx="6" fill="#ffffff" stroke="#cbd5e1" stroke-width="1.5"/>
      <text x="362" y="81" class="txt-label-main">50% to Outer Space</text>
      <text x="362" y="94" class="txt-label-sub">Escapes Earth system</text>
    </g>

    
    <g id="rerad-earth" class="ir-wave" opacity="0">
      <path d="M 260,230 Q 274,254 260,276 Q 246,298 260,322" 
            fill="none" stroke="#dc2626" stroke-width="3.5" stroke-linecap="round" filter="url(#glow)"/>
      <polygon points="260,328 267,316 253,316" fill="#dc2626"/>

      
      <rect x="282" y="260" width="220" height="36" rx="6" fill="#ffffff" stroke="#fca5a5" stroke-width="1.5"/>
      <text x="392" y="275" class="txt-label-main">50% Re-radiated to Earth</text>
      <text x="392" y="289" class="txt-label-sub" fill="#dc2626">Trapped heat warms surface</text>
    </g>

    
    <g id="rerad-side" class="ir-wave" opacity="0">
      
      <path d="M 130,185 Q 110,175 90,185 Q 70,195 50,185" 
            fill="none" stroke="#f87171" stroke-width="2" stroke-dasharray="3,3"/>
      <polygon points="44,185 54,180 54,190" fill="#f87171"/>
      
      
      <path d="M 390,185 Q 410,175 430,185 Q 450,195 470,185" 
            fill="none" stroke="#f87171" stroke-width="2" stroke-dasharray="3,3"/>
      <polygon points="476,185 466,180 466,190" fill="#f87171"/>
    </g>
  </svg>

  <script>
    let currentStep = 0;
    let timer = null;
    let isPlaying = true;

    const co2 = document.getElementById('co2-molecule');
    const incoming = document.getElementById('incoming-ir');
    const halo = document.getElementById('energy-halo');
    const vibLabel = document.getElementById('vibrate-label');
    const radSpace = document.getElementById('rerad-space');
    const radEarth = document.getElementById('rerad-earth');
    const radSide = document.getElementById('rerad-side');
    const stepBtns = document.querySelectorAll('.step-btn');
    const playBtn = document.getElementById('playBtn');

    function renderStep(idx) {
      stepBtns.forEach((btn, i) => {
        btn.classList.toggle('active', i === idx);
      });

      if (idx === 0) {
        // Step 1: IR Photon emitted from Earth
        co2.classList.remove('vibrating');
        incoming.style.opacity = '1';
        incoming.style.transform = 'translateY(0)';
        halo.style.opacity = '0';
        vibLabel.style.opacity = '0';
        radSpace.style.opacity = '0';
        radEarth.style.opacity = '0';
        radSide.style.opacity = '0';
      } else if (idx === 1) {
        // Step 2: Absorption & vibration
        co2.classList.add('vibrating');
        incoming.style.opacity = '0.15';
        incoming.style.transform = 'translateY(-15px)';
        halo.style.opacity = '0.85';
        vibLabel.style.opacity = '1';
        radSpace.style.opacity = '0';
        radEarth.style.opacity = '0';
        radSide.style.opacity = '0';
      } else if (idx === 2) {
        // Step 3: Re-radiation (50% to space, 50% back to Earth)
        co2.classList.add('vibrating');
        incoming.style.opacity = '0';
        halo.style.opacity = '0.25';
        vibLabel.style.opacity = '0';
        radSpace.style.opacity = '1';
        radEarth.style.opacity = '1';
        radSide.style.opacity = '1';
      }
    }

    function setStep(idx) {
      currentStep = idx;
      renderStep(currentStep);
    }

    function nextStep() {
      currentStep = (currentStep + 1) % 3;
      renderStep(currentStep);
    }

    function startAutoPlay() {
      stopAutoPlay();
      timer = setInterval(nextStep, 3400);
      isPlaying = true;
      playBtn.textContent = '⏸';
    }

    function stopAutoPlay() {
      if (timer) clearInterval(timer);
      timer = null;
      isPlaying = false;
      playBtn.textContent = '▶';
    }

    playBtn.addEventListener('click', () => {
      if (isPlaying) {
        stopAutoPlay();
      } else {
        nextStep();
        startAutoPlay();
      }
    });

    // Initialize
    renderStep(0);
    startAutoPlay();
  </script>
</body>
</html>

The Greenhouse Effect and Its Role in Climate

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

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      color: #1e293b;
      background: transparent;
      padding: 12px 8px;
    }

    .comparison-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 16px;
      width: 100%;
      max-width: 680px;
      margin: 0 auto;
    }

    @media (max-width: 480px) {
      .comparison-grid {
        grid-template-columns: 1fr;
        gap: 20px;
      }
    }

    .panel {
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      padding: 4px;
    }

    .panel-title {
      font-size: 15px;
      font-weight: 700;
      color: #0f172a;
      letter-spacing: -0.01em;
      margin-bottom: 6px;
      min-height: 22px;
    }

    .badge {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 5px;
      font-size: 14px;
      font-weight: 800;
      padding: 4px 12px;
      border-radius: 20px;
      margin-bottom: 10px;
    }

    .badge-cold {
      background: #e0f2fe;
      color: #0369a1;
      border: 1px solid #bae6fd;
    }

    .badge-warm {
      background: #dcfce7;
      color: #15803d;
      border: 1px solid #bbf7d0;
    }

    .scene-box {
      width: 100%;
      height: 180px;
      background: #080d1a;
      border-radius: 12px;
      overflow: hidden;
      position: relative;
    }

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

    .footer-desc {
      margin-top: 10px;
      font-size: 13px;
      font-weight: 600;
      line-height: 1.4;
      max-width: 270px;
    }

    .desc-cold {
      color: #475569;
    }

    .desc-warm {
      color: #166534;
    }

    /* Animated ray flows */
    @keyframes rayFlow {
      from { stroke-dashoffset: 20; }
      to { stroke-dashoffset: 0; }
    }

    .sun-ray {
      stroke: #facc15;
      stroke-width: 2.5;
      stroke-dasharray: 6 3;
      animation: rayFlow 1.6s linear infinite;
    }

    .heat-ray-escape {
      stroke: #f87171;
      stroke-width: 2.5;
      stroke-dasharray: 6 3;
      animation: rayFlow 1.6s linear infinite;
    }

    .heat-ray-trapped {
      stroke: #fb923c;
      stroke-width: 2.5;
      stroke-dasharray: 6 3;
      animation: rayFlow 2s linear infinite;
    }

    .heat-ray-vent {
      stroke: #f87171;
      stroke-width: 1.8;
      stroke-dasharray: 4 3;
      animation: rayFlow 2s linear infinite;
      opacity: 0.75;
    }
  </style>
</head>
<body>

  <div class="comparison-grid">
    
    
    <div class="panel">
      <div class="panel-title">Without Greenhouse Effect</div>
      <div class="badge badge-cold">❄️ −18°C / 0°F</div>
      
      <div class="scene-box">
        <svg class="scene-svg" viewBox="0 0 260 180">
          <defs>
            <radialGradient id="spaceGlowA" cx="50%" cy="50%" r="50%">
              <stop offset="0%" stop-color="#1e293b" stop-opacity="0.5"/>
              <stop offset="100%" stop-color="#080d1a" stop-opacity="0"/>
            </radialGradient>
            <radialGradient id="icePlanet" cx="40%" cy="35%" r="60%">
              <stop offset="0%" stop-color="#ffffff"/>
              <stop offset="55%" stop-color="#cbeafe"/>
              <stop offset="100%" stop-color="#38bdf8"/>
            </radialGradient>
            <marker id="arrowEsc" viewBox="0 0 10 10" refX="7" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
              <path d="M 0 1.5 L 9 5 L 0 8.5 z" fill="#f87171"/>
            </marker>
          </defs>

          
          <circle cx="130" cy="125" r="70" fill="url(#spaceGlowA)"/>

          
          <text x="14" y="24" fill="#facc15" font-size="11.5" font-weight="700">Sunlight</text>
          <line x1="28" y1="32" x2="98" y2="98" class="sun-ray"/>

          
          <text x="210" y="24" fill="#f87171" font-size="11.5" font-weight="700" text-anchor="middle">Heat escapes</text>
          <path d="M 108 96 L 210 34" class="heat-ray-escape" fill="none" marker-end="url(#arrowEsc)"/>

          
          <g>
            <circle cx="130" cy="125" r="44" fill="url(#icePlanet)"/>
            
            <path d="M 98 114 Q 115 104 136 110 Q 152 106 164 116 Q 146 130 118 126 Z" fill="#ffffff" opacity="0.85"/>
            <path d="M 108 138 Q 128 130 148 142 Q 134 158 112 152 Z" fill="#ffffff" opacity="0.85"/>
            <circle cx="130" cy="125" r="44" fill="none" stroke="#7dd3fc" stroke-width="1.5"/>
          </g>
        </svg>
      </div>

      <div class="footer-desc desc-cold">
        Frozen oceans, no liquid water, life cannot survive
      </div>
    </div>

    
    <div class="panel">
      <div class="panel-title">With Natural Greenhouse Effect</div>
      <div class="badge badge-warm">🌱 +15°C / 59°F</div>
      
      <div class="scene-box">
        <svg class="scene-svg" viewBox="0 0 260 180">
          <defs>
            <radialGradient id="spaceGlowB" cx="50%" cy="50%" r="50%">
              <stop offset="0%" stop-color="#0284c7" stop-opacity="0.25"/>
              <stop offset="100%" stop-color="#080d1a" stop-opacity="0"/>
            </radialGradient>
            <radialGradient id="earthOcean" cx="40%" cy="35%" r="60%">
              <stop offset="0%" stop-color="#38bdf8"/>
              <stop offset="60%" stop-color="#0284c7"/>
              <stop offset="100%" stop-color="#0369a1"/>
            </radialGradient>
            <marker id="arrowTrap" viewBox="0 0 10 10" refX="7" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
              <path d="M 0 1.5 L 9 5 L 0 8.5 z" fill="#fb923c"/>
            </marker>
            <marker id="arrowVent" viewBox="0 0 10 10" refX="7" refY="5" markerWidth="5" markerHeight="5" orient="auto-start-reverse">
              <path d="M 0 1.5 L 9 5 L 0 8.5 z" fill="#f87171"/>
            </marker>
          </defs>

          
          <circle cx="130" cy="125" r="58" fill="url(#spaceGlowB)"/>
          <circle cx="130" cy="125" r="58" fill="none" stroke="#38bdf8" stroke-width="1.75" stroke-dasharray="4 3" opacity="0.8"/>
          
          
          <text x="130" y="58" fill="#38bdf8" font-size="10.5" font-weight="700" text-anchor="middle" letter-spacing="0.04em">ATMOSPHERE</text>

          
          <text x="14" y="24" fill="#facc15" font-size="11.5" font-weight="700">Sunlight</text>
          <line x1="28" y1="32" x2="98" y2="98" class="sun-ray"/>

          
          <path d="M 125 78 L 195 28" class="heat-ray-vent" fill="none" marker-end="url(#arrowVent)"/>

          
          <path d="M 106 96 Q 128 72 146 84 Q 158 92 153 104" class="heat-ray-trapped" fill="none" marker-end="url(#arrowTrap)"/>

          
          <text x="210" y="88" fill="#fb923c" font-size="11.5" font-weight="700" text-anchor="middle">Heat trapped</text>

          
          <g>
            <circle cx="130" cy="125" r="44" fill="url(#earthOcean)"/>
            
            <path d="M 98 114 Q 112 100 128 106 Q 146 98 156 112 Q 140 128 116 122 Z" fill="#22c55e"/>
            <path d="M 114 132 Q 132 124 146 136 Q 138 154 118 150 Z" fill="#16a34a"/>
            <path d="M 152 126 Q 165 130 168 140 Q 158 146 150 138 Z" fill="#22c55e"/>
            <circle cx="130" cy="125" r="44" fill="none" stroke="#60a5fa" stroke-width="1.5"/>
          </g>
        </svg>
      </div>

      <div class="footer-desc desc-warm">
        Liquid oceans, stable climate, supports diverse ecosystems
      </div>
    </div>

  </div>

</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      background: #0d1527;
      color: #f8fafc;
      width: 100%;
      min-height: 100%;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      padding: 12px;
      overflow-x: hidden;
      user-select: none;
    }

    .controls {
      display: flex;
      gap: 6px;
      margin-bottom: 8px;
      flex-wrap: wrap;
      justify-content: center;
      z-index: 10;
    }

    .btn {
      background: rgba(255, 255, 255, 0.1);
      border: 1px solid rgba(255, 255, 255, 0.2);
      color: #e2e8f0;
      padding: 6px 12px;
      font-size: 13px;
      font-weight: 500;
      border-radius: 20px;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      transition: background 0.2s, box-shadow 0.2s;
    }

    .btn:hover {
      background: rgba(255, 255, 255, 0.18);
    }

    .btn.active {
      background: #0284c7;
      border-color: #38bdf8;
      box-shadow: 0 0 10px rgba(56, 189, 248, 0.4);
      color: #ffffff;
    }

    .svg-container {
      width: 100%;
      max-width: 620px;
      aspect-ratio: 4 / 3;
      position: relative;
    }

    svg {
      width: 100%;
      height: 100%;
      display: block;
      overflow: visible;
    }

    /* Wave animations */
    @keyframes flowIn {
      from { stroke-dashoffset: 80; }
      to { stroke-dashoffset: 0; }
    }

    @keyframes flowOut {
      from { stroke-dashoffset: 0; }
      to { stroke-dashoffset: -80; }
    }

    @keyframes earthPulse {
      0%, 100% { fill-opacity: 0.15; filter: drop-shadow(0 0 4px #f59e0b); }
      50% { fill-opacity: 0.45; filter: drop-shadow(0 0 14px #ef4444); }
    }

    .wave-incoming {
      stroke-dasharray: 8, 4;
      animation: flowIn 2s linear infinite;
    }

    .wave-outgoing {
      stroke-dasharray: 12, 6;
      animation: flowOut 2.8s linear infinite;
    }

    .warm-glow {
      animation: earthPulse 3s ease-in-out infinite;
    }

    /* Step visibility transitions */
    .step-el {
      transition: opacity 0.4s ease, transform 0.4s ease;
    }

    .hidden {
      opacity: 0.08 !important;
      pointer-events: none;
    }

    .label-box {
      font-size: 11px;
      font-weight: 600;
      letter-spacing: 0.2px;
    }
  </style>
</head>
<body>

  <div class="controls">
    <button class="btn active" id="btn-all" onclick="setStep(0)">✦ Full Process</button>
    <button class="btn" id="btn-1" onclick="setStep(1)">1. Incoming Solar</button>
    <button class="btn" id="btn-2" onclick="setStep(2)">2. Earth Warms</button>
    <button class="btn" id="btn-3" onclick="setStep(3)">3. Infrared Emission</button>
  </div>

  <div class="svg-container">
    <svg viewBox="0 0 600 450" preserveAspectRatio="xMidYMid meet">
      <defs>
        
        <radialGradient id="sunGlow" cx="0%" cy="50%" r="90%">
          <stop offset="0%" stop-color="#fffbeb" />
          <stop offset="35%" stop-color="#fbbf24" />
          <stop offset="70%" stop-color="#f59e0b" stop-opacity="0.8" />
          <stop offset="100%" stop-color="#d97706" stop-opacity="0" />
        </radialGradient>

        <linearGradient id="earthGrad" x1="0%" y1="0%" x2="100%" y2="100%">
          <stop offset="0%" stop-color="#0284c7" />
          <stop offset="45%" stop-color="#0f766e" />
          <stop offset="90%" stop-color="#15803d" />
        </linearGradient>

        <linearGradient id="atmoGrad" x1="0%" y1="0%" x2="100%" y2="0%">
          <stop offset="0%" stop-color="#38bdf8" stop-opacity="0.0" />
          <stop offset="30%" stop-color="#38bdf8" stop-opacity="0.22" />
          <stop offset="100%" stop-color="#0284c7" stop-opacity="0.38" />
        </linearGradient>

        
        <marker id="arrow-solar" markerWidth="6" markerHeight="6" refX="5" refY="3" orient="auto">
          <path d="M0,0 L6,3 L0,6 Z" fill="#38bdf8" />
        </marker>
        <marker id="arrow-ir" markerWidth="6" markerHeight="6" refX="5" refY="3" orient="auto">
          <path d="M0,0 L6,3 L0,6 Z" fill="#f87171" />
        </marker>

        
        <filter id="glow-sun" x="-50%" y="-50%" width="200%" height="200%">
          <feGaussianBlur stdDeviation="8" result="blur" />
          <feMerge>
            <feMergeNode in="blur" />
            <feMergeNode in="SourceGraphic" />
          </feMerge>
        </filter>
      </defs>

      
      <path d="M 330 0 C 370 140, 370 310, 330 450 L 600 450 L 600 0 Z" fill="url(#atmoGrad)" />
      <path d="M 330 0 C 370 140, 370 310, 330 450" fill="none" stroke="#38bdf8" stroke-width="1.5" stroke-dasharray="4,4" opacity="0.6" />
      <text x="345" y="32" fill="#7dd3fc" font-size="11" font-weight="600" opacity="0.9" letter-spacing="1">ATMOSPHERE</text>

      
      <g transform="translate(-40, 225)">
        <circle cx="0" cy="0" r="115" fill="url(#sunGlow)" />
        <circle cx="0" cy="0" r="65" fill="#fef08a" filter="url(#glow-sun)" />
        <text x="50" y="5" fill="#78350f" font-size="13" font-weight="700" text-anchor="middle">SUN</text>
      </g>

      
      <g>
        
        <path d="M 450 0 C 490 140, 490 310, 450 450 L 600 450 L 600 0 Z" fill="url(#earthGrad)" />
        <path d="M 450 0 C 490 140, 490 310, 450 450" fill="none" stroke="#22c55e" stroke-width="2.5" />

        
        <path id="el-step2" class="step-el warm-glow" d="M 450 0 C 490 140, 490 310, 450 450 L 485 450 C 520 310, 520 140, 485 0 Z" fill="#ef4444" opacity="0.4" />
        
        <text x="510" y="230" fill="#ffffff" font-size="15" font-weight="700" letter-spacing="1">EARTH</text>
      </g>

      
      
      <g id="el-step1" class="step-el">
        
        <path class="wave-incoming" fill="none" stroke="#38bdf8" stroke-width="2.5" marker-end="url(#arrow-solar)"
          d="M 45 130 
             q 10 -10, 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0
             L 460 130" />

        
        <path class="wave-incoming" fill="none" stroke="#facc15" stroke-width="2.5" marker-end="url(#arrow-solar)"
          d="M 50 225 
             q 10 -10, 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0
             L 470 225" />

        
        <path class="wave-incoming" fill="none" stroke="#38bdf8" stroke-width="2.5" marker-end="url(#arrow-solar)"
          d="M 45 320 
             q 10 -10, 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0 t 20 0
             L 460 320" />

        
        <g transform="translate(100, 80)">
          <rect x="0" y="0" width="220" height="26" rx="6" fill="#0f172a" stroke="#38bdf8" stroke-width="1.2" opacity="0.95" />
          <text class="label-box" x="110" y="17" fill="#38bdf8" text-anchor="middle">Short-wavelength solar (visible/UV)</text>
        </g>
      </g>

      
      <g id="el-step2-label" class="step-el">
        <g transform="translate(370, 395)">
          <rect x="0" y="0" width="190" height="26" rx="6" fill="#0f172a" stroke="#f59e0b" stroke-width="1.2" opacity="0.95" />
          <text class="label-box" x="95" y="17" fill="#fbbf24" text-anchor="middle">Earth absorbs and warms</text>
        </g>
      </g>

      
      
      <g id="el-step3" class="step-el">
        
        <path class="wave-outgoing" fill="none" stroke="#f87171" stroke-width="3.5" marker-end="url(#arrow-ir)"
          d="M 460 175 
             q -25 18, -50 0 t -50 0 t -50 0 t -50 0 t -50 0
             L 190 175" />

        
        <path class="wave-outgoing" fill="none" stroke="#fb923c" stroke-width="3.5" marker-end="url(#arrow-ir)"
          d="M 465 275 
             q -25 18, -50 0 t -50 0 t -50 0 t -50 0 t -50 0
             L 195 275" />

        
        <g transform="translate(170, 350)">
          <rect x="0" y="0" width="225" height="26" rx="6" fill="#0f172a" stroke="#f87171" stroke-width="1.2" opacity="0.95" />
          <text class="label-box" x="112" y="17" fill="#f87171" text-anchor="middle">Long-wavelength thermal infrared</text>
        </g>
      </g>

      
      <g transform="translate(16, 400)">
        <rect x="0" y="0" width="145" height="40" rx="6" fill="rgba(15, 23, 42, 0.85)" stroke="rgba(255,255,255,0.15)" stroke-width="1" />
        <path d="M 12 14 q 4 -4, 8 0 t 8 0" fill="none" stroke="#38bdf8" stroke-width="2" />
        <text x="34" y="17" fill="#94a3b8" font-size="10" font-weight="600">Short (High energy)</text>
        <path d="M 12 28 q 8 6, 16 0" fill="none" stroke="#f87171" stroke-width="2.5" />
        <text x="34" y="32" fill="#94a3b8" font-size="10" font-weight="600">Long (Thermal)</text>
      </g>
    </svg>
  </div>

  <script>
    let currentStep = 0;
    const step1 = document.getElementById('el-step1');
    const step2 = document.getElementById('el-step2');
    const step2Label = document.getElementById('el-step2-label');
    const step3 = document.getElementById('el-step3');

    const buttons = [
      document.getElementById('btn-all'),
      document.getElementById('btn-1'),
      document.getElementById('btn-2'),
      document.getElementById('btn-3')
    ];

    function setStep(step) {
      currentStep = step;
      buttons.forEach((b, i) => b.classList.toggle('active', i === step));

      if (step === 0) {
        step1.classList.remove('hidden');
        step2.classList.remove('hidden');
        step2Label.classList.remove('hidden');
        step3.classList.remove('hidden');
      } else if (step === 1) {
        step1.classList.remove('hidden');
        step2.classList.add('hidden');
        step2Label.classList.add('hidden');
        step3.classList.add('hidden');
      } else if (step === 2) {
        step1.classList.remove('hidden');
        step2.classList.remove('hidden');
        step2Label.classList.remove('hidden');
        step3.classList.add('hidden');
      } else if (step === 3) {
        step1.classList.add('hidden');
        step2.classList.remove('hidden');
        step2Label.classList.add('hidden');
        step3.classList.remove('hidden');
      }
    }
  </script>
</body>
</html>

UK-GCSE-SCIENCE-CHEM-EA-02-01

Aligned learning resources

Related diagrams