<!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;
      color: #1e2945;
      background: transparent;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
    }
    .controls {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      width: 100%;
      margin-bottom: 8px;
    }
    .btn {
      background: #f1f5f9;
      border: 1px solid #cbd5e1;
      border-radius: 6px;
      padding: 6px 12px;
      font-size: 13px;
      font-weight: 600;
      color: #1e2945;
      cursor: pointer;
      transition: background-color 0.2s, border-color 0.2s, color 0.2s;
    }
    .btn.active {
      background: #2563eb;
      border-color: #2563eb;
      color: #ffffff;
    }
    .btn-play {
      display: flex;
      align-items: center;
      justify-content: center;
      width: 32px;
      height: 32px;
      padding: 0;
      border-radius: 50%;
    }
    .chart-area {
      position: relative;
      width: 100%;
      max-width: 520px;
      height: 230px;
      display: flex;
      align-items: flex-end;
      justify-content: space-around;
      padding-bottom: 28px;
      border-bottom: 2px solid #e2e8f0;
    }
    .col-group {
      display: flex;
      flex-direction: column;
      align-items: center;
      width: 20%;
      height: 100%;
      justify-content: flex-end;
      position: relative;
    }
    .total-badge {
      font-size: 14px;
      font-weight: 700;
      color: #1e2945;
      margin-bottom: 6px;
      transition: transform 0.3s ease, opacity 0.3s ease;
      white-space: nowrap;
    }
    .bar-stack {
      width: 100%;
      display: flex;
      flex-direction: column-reverse;
      gap: 3px;
    }
    .block-principal {
      height: 100px;
      background: #2563eb;
      border-radius: 4px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: #ffffff;
      font-size: 13px;
      font-weight: 700;
    }
    .block-interest {
      height: 22px;
      background: #10b981;
      border-radius: 4px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: #ffffff;
      font-size: 12px;
      font-weight: 700;
      opacity: 0;
      transform: scaleY(0);
      transform-origin: bottom;
      transition: opacity 0.35s ease, transform 0.35s ease;
    }
    .block-interest.visible {
      opacity: 1;
      transform: scaleY(1);
    }
    .col-group.inactive {
      opacity: 0.35;
    }
    .col-group {
      transition: opacity 0.3s ease;
    }
    .year-label {
      position: absolute;
      bottom: -24px;
      font-size: 13px;
      font-weight: 600;
      color: #64748b;
    }
    .col-group.active .year-label {
      color: #1e2945;
      font-weight: 700;
    }
    .legend {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 18px;
      margin-top: 12px;
      font-size: 13px;
      font-weight: 600;
    }
    .legend-item {
      display: flex;
      align-items: center;
      gap: 6px;
    }
    .legend-color {
      width: 14px;
      height: 14px;
      border-radius: 3px;
    }
    .bg-principal { background: #2563eb; }
    .bg-interest { background: #10b981; }
  </style>
</head>
<body>

  <div class="controls">
    <button class="btn btn-play" id="playBtn" aria-label="Play/Pause">⏸</button>
    <button class="btn active" data-step="0">Year 0</button>
    <button class="btn" data-step="1">Year 1</button>
    <button class="btn" data-step="2">Year 2</button>
    <button class="btn" data-step="3">Year 3</button>
  </div>

  <div class="chart-area">
    
    <div class="col-group" id="col-0">
      <div class="total-badge">$500</div>
      <div class="bar-stack">
        <div class="block-principal">$500</div>
      </div>
      <div class="year-label">Yr 0</div>
    </div>

    
    <div class="col-group inactive" id="col-1">
      <div class="total-badge">$530</div>
      <div class="bar-stack">
        <div class="block-principal">$500</div>
        <div class="block-interest" id="int-1-1">+$30</div>
      </div>
      <div class="year-label">Yr 1</div>
    </div>

    
    <div class="col-group inactive" id="col-2">
      <div class="total-badge">$560</div>
      <div class="bar-stack">
        <div class="block-principal">$500</div>
        <div class="block-interest" id="int-2-1">+$30</div>
        <div class="block-interest" id="int-2-2">+$30</div>
      </div>
      <div class="year-label">Yr 2</div>
    </div>

    
    <div class="col-group inactive" id="col-3">
      <div class="total-badge">$590</div>
      <div class="bar-stack">
        <div class="block-principal">$500</div>
        <div class="block-interest" id="int-3-1">+$30</div>
        <div class="block-interest" id="int-3-2">+$30</div>
        <div class="block-interest" id="int-3-3">+$30</div>
      </div>
      <div class="year-label">Yr 3</div>
    </div>
  </div>

  <div class="legend">
    <div class="legend-item">
      <div class="legend-color bg-principal"></div>
      <span>Principal</span>
    </div>
    <div class="legend-item">
      <div class="legend-color bg-interest"></div>
      <span>+$30 Interest/yr</span>
    </div>
  </div>

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

    const stepButtons = document.querySelectorAll('.controls .btn[data-step]');
    const playBtn = document.getElementById('playBtn');

    function updateView(step) {
      currentStep = step;

      stepButtons.forEach((btn, idx) => {
        btn.classList.toggle('active', idx === step);
      });

      for (let i = 0; i <= 3; i++) {
        const col = document.getElementById(`col-${i}`);
        if (i <= step) {
          col.classList.remove('inactive');
          col.classList.toggle('active', i === step);
        } else {
          col.classList.add('inactive');
          col.classList.remove('active');
        }
      }

      // Toggle interest block animations
      document.getElementById('int-1-1').classList.toggle('visible', step >= 1);
      document.getElementById('int-2-1').classList.toggle('visible', step >= 2);
      document.getElementById('int-2-2').classList.toggle('visible', step >= 2);
      document.getElementById('int-3-1').classList.toggle('visible', step >= 3);
      document.getElementById('int-3-2').classList.toggle('visible', step >= 3);
      document.getElementById('int-3-3').classList.toggle('visible', step >= 3);
    }

    function nextStep() {
      const next = (currentStep + 1) % 4;
      updateView(next);
    }

    function startAutoPlay() {
      isPlaying = true;
      playBtn.textContent = '⏸';
      clearInterval(timer);
      timer = setInterval(nextStep, 3000);
    }

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

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

    stepButtons.forEach(btn => {
      btn.addEventListener('click', () => {
        pauseAutoPlay();
        updateView(parseInt(btn.getAttribute('data-step'), 10));
      });
    });

    updateView(0);
    startAutoPlay();
  </script>
</body>
</html>

Calculating Simple Interest and Future Value

<!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;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    }

    body {
      width: 100%;
      background: transparent;
      color: #1e293b;
      padding: 16px 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100vh;
    }

    .converter-container {
      width: 100%;
      max-width: 440px;
      display: flex;
      flex-direction: column;
      gap: 16px;
    }

    .unit-pills {
      display: flex;
      gap: 8px;
      width: 100%;
    }

    .pill {
      flex: 1;
      border: 1px solid #cbd5e1;
      background: #f8fafc;
      padding: 8px 4px;
      border-radius: 8px;
      text-align: center;
      cursor: pointer;
      font-size: 13px;
      font-weight: 600;
      color: #475569;
      transition: background-color 0.2s ease, border-color 0.2s ease, color 0.2s ease;
      user-select: none;
    }

    .pill.active {
      background: #2563eb;
      color: #ffffff;
      border-color: #2563eb;
      box-shadow: 0 2px 6px rgba(37, 99, 235, 0.25);
    }

    .pill .formula {
      display: block;
      font-size: 11px;
      font-weight: 500;
      opacity: 0.9;
      margin-top: 2px;
    }

    .interactive-section {
      width: 100%;
      display: flex;
      flex-direction: column;
      gap: 16px;
    }

    .math-row {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 10px;
      font-size: 20px;
      font-weight: 700;
      color: #0f172a;
      padding: 4px 0;
    }

    .frac {
      display: inline-flex;
      flex-direction: column;
      vertical-align: middle;
      text-align: center;
      font-size: 18px;
      line-height: 1.1;
    }

    .frac-top {
      border-bottom: 2px solid #0f172a;
      padding-bottom: 2px;
      color: #2563eb;
    }

    .frac-bot {
      padding-top: 2px;
      color: #64748b;
    }

    .result-badge {
      background: #eff6ff;
      border: 1px solid #bfdbfe;
      color: #1d4ed8;
      padding: 4px 10px;
      border-radius: 6px;
      font-size: 18px;
      font-weight: 700;
    }

    .slider-wrap {
      display: flex;
      flex-direction: column;
      gap: 8px;
    }

    .slider-labels {
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-size: 12px;
      font-weight: 600;
      color: #64748b;
    }

    input[type="range"] {
      -webkit-appearance: none;
      appearance: none;
      width: 100%;
      height: 8px;
      border-radius: 4px;
      background: #e2e8f0;
      outline: none;
      cursor: pointer;
    }

    input[type="range"]::-webkit-slider-thumb {
      -webkit-appearance: none;
      appearance: none;
      width: 22px;
      height: 22px;
      border-radius: 50%;
      background: #2563eb;
      cursor: pointer;
      box-shadow: 0 1px 4px rgba(0,0,0,0.25);
    }

    input[type="range"]::-moz-range-thumb {
      width: 22px;
      height: 22px;
      border-radius: 50%;
      background: #2563eb;
      cursor: pointer;
      border: none;
      box-shadow: 0 1px 4px rgba(0,0,0,0.25);
    }

    .bar-section {
      display: flex;
      flex-direction: column;
      gap: 6px;
    }

    .bar-container {
      position: relative;
      width: 100%;
      height: 20px;
      background: #e2e8f0;
      border-radius: 6px;
      overflow: hidden;
    }

    .bar-fill {
      height: 100%;
      background: linear-gradient(90deg, #3b82f6, #2563eb);
      width: 25%;
      transition: width 0.1s ease-out;
    }

    .bar-mark {
      position: absolute;
      top: 0;
      bottom: 0;
      left: 50%;
      width: 2px;
      background: #ffffff;
      opacity: 0.9;
    }

    .bar-sublabel {
      display: flex;
      justify-content: space-between;
      font-size: 11px;
      font-weight: 600;
      color: #64748b;
      padding: 0 2px;
    }

    .presets-label {
      font-size: 11px;
      font-weight: 600;
      text-transform: uppercase;
      letter-spacing: 0.5px;
      color: #94a3b8;
      text-align: center;
      margin-bottom: -4px;
    }

    .presets {
      display: flex;
      justify-content: center;
      flex-wrap: wrap;
      gap: 6px;
      width: 100%;
    }

    .btn-preset {
      flex: 1 1 54px;
      max-width: 80px;
      border: 1px solid #cbd5e1;
      background: #ffffff;
      border-radius: 6px;
      padding: 6px 4px;
      font-size: 12px;
      font-weight: 600;
      color: #334155;
      cursor: pointer;
      text-align: center;
      transition: background-color 0.15s ease, border-color 0.15s ease;
    }

    .btn-preset:hover {
      background: #f1f5f9;
      border-color: #94a3b8;
    }

    .btn-preset:active {
      background: #e2e8f0;
    }
  </style>
</head>
<body>

  <div class="converter-container">
    <div class="unit-pills">
      <div class="pill active" id="btn-months" onclick="setMode('months')">
        Months
        <span class="formula">t = m / 12</span>
      </div>
      <div class="pill" id="btn-weeks" onclick="setMode('weeks')">
        Weeks
        <span class="formula">t = w / 52</span>
      </div>
      <div class="pill" id="btn-days" onclick="setMode('days')">
        Days
        <span class="formula">t = d / 365</span>
      </div>
    </div>

    <div class="interactive-section">
      <div class="math-row">
        <span>t =</span>
        <div class="frac">
          <span class="frac-top" id="frac-num">6</span>
          <span class="frac-bot" id="frac-den">12</span>
        </div>
        <span>=</span>
        <span class="result-badge" id="dec-val">0.5 yr</span>
      </div>

      <div class="slider-wrap">
        <input type="range" id="time-slider" min="1" max="24" value="6" oninput="updateTime(this.value)">
        <div class="slider-labels">
          <span id="min-lbl">1 mo</span>
          <span id="curr-lbl" style="color:#2563eb; font-weight:700;">6 months</span>
          <span id="max-lbl">24 mo</span>
        </div>
      </div>

      <div class="bar-section">
        <div class="bar-container">
          <div class="bar-fill" id="meter-fill"></div>
          <div class="bar-mark"></div>
        </div>
        <div class="bar-sublabel">
          <span>0 yr</span>
          <span style="transform: translateX(4px);">1 yr (12 mo)</span>
          <span>2 yr (24 mo)</span>
        </div>
      </div>

      <div class="presets-label">Quick Presets</div>
      <div class="presets" id="preset-container"></div>
    </div>
  </div>

  <script>
    const modes = {
      months: {
        den: 12,
        min: 1,
        max: 24,
        step: 1,
        unit: 'mo',
        unitFull: 'months',
        presets: [3, 6, 12, 18, 24],
        midLabel: '1 yr (12 mo)',
        maxLabel: '2 yr (24 mo)'
      },
      weeks: {
        den: 52,
        min: 1,
        max: 104,
        step: 1,
        unit: 'wk',
        unitFull: 'weeks',
        presets: [13, 26, 52, 78, 104],
        midLabel: '1 yr (52 wk)',
        maxLabel: '2 yr (104 wk)'
      },
      days: {
        den: 365,
        min: 30,
        max: 730,
        step: 5,
        unit: 'd',
        unitFull: 'days',
        presets: [90, 180, 365, 548, 730],
        midLabel: '1 yr (365 d)',
        maxLabel: '2 yr (730 d)'
      }
    };

    let currentMode = 'months';

    function setMode(modeKey) {
      currentMode = modeKey;
      const m = modes[modeKey];

      document.querySelectorAll('.pill').forEach(p => p.classList.remove('active'));
      document.getElementById('btn-' + modeKey).classList.add('active');

      const slider = document.getElementById('time-slider');
      slider.min = m.min;
      slider.max = m.max;
      slider.step = m.step;

      let defaultVal = modeKey === 'months' ? 6 : (modeKey === 'weeks' ? 26 : 180);
      slider.value = defaultVal;

      document.getElementById('frac-den').textContent = m.den;
      document.getElementById('min-lbl').textContent = m.min + ' ' + m.unit;
      document.getElementById('max-lbl').textContent = m.max + ' ' + m.unit;

      const subLabels = document.querySelectorAll('.bar-sublabel span');
      if (subLabels.length >= 3) {
        subLabels[1].textContent = m.midLabel;
        subLabels[2].textContent = m.maxLabel;
      }

      const presetBox = document.getElementById('preset-container');
      presetBox.innerHTML = '';
      m.presets.forEach(p => {
        const btn = document.createElement('button');
        btn.className = 'btn-preset';
        btn.textContent = p + ' ' + m.unit;
        btn.onclick = () => setVal(p);
        presetBox.appendChild(btn);
      });

      updateTime(defaultVal);
    }

    function setVal(val) {
      document.getElementById('time-slider').value = val;
      updateTime(val);
    }

    function updateTime(val) {
      val = parseFloat(val);
      const m = modes[currentMode];
      const years = val / m.den;

      document.getElementById('frac-num').textContent = val;
      
      let yrFormatted = Number.isInteger(years) ? years.toString() : (Math.round(years * 100) / 100).toString();
      document.getElementById('dec-val').textContent = yrFormatted + ' yr';

      document.getElementById('curr-lbl').textContent = val + ' ' + m.unitFull;

      const pct = Math.min(100, Math.max(0, (years / 2) * 100));
      document.getElementById('meter-fill').style.width = pct + '%';
    }

    setMode('months');
  </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;
      color: #1e2945;
      background: transparent;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100vh;
      padding: 12px;
      user-select: none;
    }
    .wrapper {
      width: 100%;
      max-width: 360px;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 14px;
    }
    .btn-group {
      display: flex;
      gap: 8px;
      width: 100%;
      justify-content: center;
    }
    .btn {
      flex: 1;
      padding: 8px 0;
      font-size: 15px;
      font-weight: 700;
      border: 1.5px solid #cbd5e1;
      border-radius: 8px;
      background: #f8fafc;
      color: #1e2945;
      cursor: pointer;
      transition: background 0.2s, border-color 0.2s, color 0.2s, box-shadow 0.2s;
      text-align: center;
    }
    .btn:hover {
      border-color: #22b7ff;
    }
    .btn.active {
      background: #22b7ff;
      border-color: #0284c7;
      color: #ffffff;
      box-shadow: 0 2px 6px rgba(34, 183, 255, 0.35);
    }
    .svg-container {
      width: 100%;
      max-width: 290px;
      aspect-ratio: 400 / 330;
      position: relative;
    }
    svg {
      width: 100%;
      height: 100%;
      overflow: visible;
      cursor: pointer;
    }
    .sector {
      transition: fill 0.25s, stroke 0.25s;
    }
    .sector-text {
      font-size: 38px;
      font-weight: 800;
      fill: #1e2945;
      text-anchor: middle;
      dominant-baseline: central;
      pointer-events: none;
      transition: fill 0.25s, opacity 0.25s;
    }
    .op-label {
      font-size: 22px;
      font-weight: 700;
      fill: #64748b;
      text-anchor: middle;
      dominant-baseline: central;
      pointer-events: none;
    }
    .cover-overlay {
      opacity: 0;
      transition: opacity 0.25s;
      pointer-events: none;
    }
    .cover-overlay.active {
      opacity: 1;
    }
    .result-box {
      width: 100%;
      min-height: 58px;
      display: flex;
      align-items: center;
      justify-content: center;
      background: #f0fdf4;
      border: 1.5px solid #86efac;
      border-radius: 10px;
      font-size: 22px;
      font-weight: 700;
      color: #166534;
      padding: 6px 12px;
    }
    .frac {
      display: inline-flex;
      flex-direction: column;
      vertical-align: middle;
      text-align: center;
      padding: 0 4px;
      font-size: 0.9em;
      line-height: 1.1;
    }
    .frac-top {
      border-bottom: 2px solid currentColor;
      padding-bottom: 2px;
    }
    .frac-bot {
      padding-top: 2px;
    }
  </style>
</head>
<body>

  <div class="wrapper">
    <div class="btn-group">
      <button class="btn active" onclick="selectVar('I')">Cover I</button>
      <button class="btn" onclick="selectVar('P')">Cover P</button>
      <button class="btn" onclick="selectVar('r')">Cover r</button>
      <button class="btn" onclick="selectVar('t')">Cover t</button>
    </div>

    <div class="svg-container">
      <svg viewBox="0 0 400 330">
        
        <g stroke="#94a3b8" stroke-width="3" stroke-linecap="round">
          
          <polygon id="sec-I" class="sector" points="200,18 296,165 104,165" fill="#e0f2fe" stroke="#38bdf8" onclick="selectVar('I')" />
          
          
          <polygon id="sec-P" class="sector" points="104,165 168,165 136,315 16,315" fill="#f1f5f9" stroke="#94a3b8" onclick="selectVar('P')" />
          
          
          <polygon id="sec-r" class="sector" points="168,165 232,165 264,315 136,315" fill="#f1f5f9" stroke="#94a3b8" onclick="selectVar('r')" />
          
          
          <polygon id="sec-t" class="sector" points="232,165 296,165 384,315 264,315" fill="#f1f5f9" stroke="#94a3b8" onclick="selectVar('t')" />
        </g>

        
        <polygon points="200,18 384,315 16,315" fill="none" stroke="#1e2945" stroke-width="4" stroke-linejoin="round" pointer-events="none" />
        
        
        <line x1="104" y1="165" x2="296" y2="165" stroke="#1e2945" stroke-width="4" pointer-events="none" />

        
        <line x1="168" y1="165" x2="136" y2="315" stroke="#1e2945" stroke-width="3" pointer-events="none" />
        <line x1="232" y1="165" x2="264" y2="315" stroke="#1e2945" stroke-width="3" pointer-events="none" />

        
        <text x="152" y="240" class="op-label">×</text>
        <text x="248" y="240" class="op-label">×</text>

        
        <text id="lbl-I" x="200" y="115" class="sector-text">I</text>
        <text id="lbl-P" x="102" y="242" class="sector-text">P</text>
        <text id="lbl-r" x="200" y="242" class="sector-text">r</text>
        <text id="lbl-t" x="298" y="242" class="sector-text">t</text>

        
        <g id="cov-I" class="cover-overlay active">
          <polygon points="200,18 296,165 104,165" fill="#0284c7" opacity="0.88" />
          <text x="200" y="115" font-size="28" font-weight="700" fill="#ffffff" text-anchor="middle" dominant-baseline="central">✋</text>
        </g>

        <g id="cov-P" class="cover-overlay">
          <polygon points="104,165 168,165 136,315 16,315" fill="#0284c7" opacity="0.88" />
          <text x="102" y="242" font-size="26" font-weight="700" fill="#ffffff" text-anchor="middle" dominant-baseline="central">✋</text>
        </g>

        <g id="cov-r" class="cover-overlay">
          <polygon points="168,165 232,165 264,315 136,315" fill="#0284c7" opacity="0.88" />
          <text x="200" y="242" font-size="26" font-weight="700" fill="#ffffff" text-anchor="middle" dominant-baseline="central">✋</text>
        </g>

        <g id="cov-t" class="cover-overlay">
          <polygon points="232,165 296,165 384,315 264,315" fill="#0284c7" opacity="0.88" />
          <text x="298" y="242" font-size="26" font-weight="700" fill="#ffffff" text-anchor="middle" dominant-baseline="central">✋</text>
        </g>
      </svg>
    </div>

    <div id="resultBox" class="result-box">
      I = P · r · t
    </div>
  </div>

  <script>
    const formulas = {
      'I': 'I = P · r · t',
      'P': 'P = <span class="frac"><span class="frac-top">I</span><span class="frac-bot">r · t</span></span>',
      'r': 'r = <span class="frac"><span class="frac-top">I</span><span class="frac-bot">P · t</span></span>',
      't': 't = <span class="frac"><span class="frac-top">I</span><span class="frac-bot">P · r</span></span>'
    };

    const vars = ['I', 'P', 'r', 't'];

    function selectVar(v) {
      const buttons = document.querySelectorAll('.btn');
      vars.forEach((name, i) => {
        const isActive = name === v;
        buttons[i].classList.toggle('active', isActive);

        const overlay = document.getElementById('cov-' + name);
        if (overlay) {
          overlay.classList.toggle('active', isActive);
        }

        const sector = document.getElementById('sec-' + name);
        if (sector) {
          sector.setAttribute('fill', isActive ? '#e0f2fe' : '#f8fafc');
        }
      });

      const resBox = document.getElementById('resultBox');
      resBox.innerHTML = formulas[v];
    }
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      color: #1e293b;
      background: transparent;
      padding: 10px;
      display: flex;
      flex-direction: column;
      gap: 12px;
      user-select: none;
    }

    /* Equation Bar */
    .equation-bar {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      padding: 10px;
    }

    .eq-pill {
      font-size: 26px;
      font-weight: 700;
      font-style: italic;
      font-family: 'Cambria Math', 'Times New Roman', serif;
      padding: 4px 18px;
      border-radius: 24px;
      cursor: pointer;
      border: 2px solid transparent;
      box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
      transition: box-shadow 0.2s ease, opacity 0.2s ease;
      line-height: 1.2;
    }

    .eq-pill:focus-visible {
      outline: 2px solid #000;
    }

    .eq-op {
      font-size: 24px;
      font-weight: 600;
      color: #94a3b8;
    }

    /* Coordinated Colors */
    .var-i {
      color: #059669;
      background-color: #d1fae5;
    }
    .var-p {
      color: #2563eb;
      background-color: #dbeafe;
    }
    .var-r {
      color: #4f46e5;
      background-color: #e0e7ff;
    }
    .var-t {
      color: #d97706;
      background-color: #fef3c7;
    }

    /* Active Highlight States */
    .active.var-i { box-shadow: 0 0 0 2px #059669, 0 4px 12px rgba(5, 150, 105, 0.25); }
    .active.var-p { box-shadow: 0 0 0 2px #2563eb, 0 4px 12px rgba(37, 99, 235, 0.25); }
    .active.var-r { box-shadow: 0 0 0 2px #4f46e5, 0 4px 12px rgba(79, 70, 229, 0.25); }
    .active.var-t { box-shadow: 0 0 0 2px #d97706, 0 4px 12px rgba(217, 119, 6, 0.25); }

    /* Dimmed State when one variable is focused */
    .dimmed {
      opacity: 0.45;
    }

    /* Cards Grid */
    .cards-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 10px;
    }

    @media (max-width: 580px) {
      .cards-grid {
        grid-template-columns: repeat(2, 1fr);
      }
      .eq-pill {
        font-size: 20px;
        padding: 3px 12px;
      }
      .eq-op {
        font-size: 18px;
      }
    }

    .detail-card {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 10px 12px;
      display: flex;
      flex-direction: column;
      gap: 6px;
      cursor: pointer;
      border-top-width: 4px;
      transition: box-shadow 0.2s ease, opacity 0.2s ease;
    }

    .detail-card.card-i { border-top-color: #059669; }
    .detail-card.card-p { border-top-color: #2563eb; }
    .detail-card.card-r { border-top-color: #4f46e5; }
    .detail-card.card-t { border-top-color: #d97706; }

    .card-head {
      display: flex;
      align-items: baseline;
      gap: 6px;
    }

    .card-sym {
      font-size: 18px;
      font-weight: 700;
      font-family: 'Cambria Math', 'Times New Roman', serif;
      font-style: italic;
    }

    .card-title {
      font-size: 13px;
      font-weight: 700;
      color: #1e293b;
      line-height: 1.2;
    }

    .card-desc {
      font-size: 12px;
      color: #475569;
      line-height: 1.35;
    }

    .card-rule {
      font-size: 11px;
      font-weight: 600;
      color: #64748b;
      background: #f8fafc;
      padding: 4px 6px;
      border-radius: 4px;
      border: 1px dashed #cbd5e1;
      line-height: 1.3;
    }

    .card-example {
      margin-top: auto;
      font-size: 12px;
      font-weight: 700;
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding-top: 4px;
      border-top: 1px solid #f1f5f9;
    }

    .ex-label {
      font-size: 10px;
      font-weight: 600;
      color: #94a3b8;
      text-transform: uppercase;
      letter-spacing: 0.5px;
    }

    .card-i .ex-val { color: #059669; }
    .card-p .ex-val { color: #2563eb; }
    .card-r .ex-val { color: #4f46e5; }
    .card-t .ex-val { color: #d97706; }

    /* Interactive Live Math Banner */
    .example-banner {
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 10px 14px;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 10px;
      flex-wrap: wrap;
      font-size: 15px;
      font-weight: 600;
      color: #334155;
    }

    .calc-part {
      padding: 4px 10px;
      border-radius: 6px;
      cursor: pointer;
      transition: box-shadow 0.2s ease, opacity 0.2s ease;
      font-weight: 700;
      display: inline-flex;
      align-items: center;
      gap: 4px;
    }

    .calc-part span.sub {
      font-size: 10px;
      font-weight: 600;
      opacity: 0.8;
      font-family: system-ui, sans-serif;
    }
  </style>
</head>
<body>

  
  <div class="equation-bar" role="toolbar" aria-label="Formula Selector">
    <div class="eq-pill var-i active" data-var="i" onclick="selectVar('i')" title="Interest">I</div>
    <div class="eq-op">=</div>
    <div class="eq-pill var-p active" data-var="p" onclick="selectVar('p')" title="Principal">P</div>
    <div class="eq-op">·</div>
    <div class="eq-pill var-r active" data-var="r" onclick="selectVar('r')" title="Annual Rate">r</div>
    <div class="eq-op">·</div>
    <div class="eq-pill var-t active" data-var="t" onclick="selectVar('t')" title="Time in Years">t</div>
  </div>

  
  <div class="cards-grid">
    
    <div class="detail-card card-i active" data-var="i" onclick="selectVar('i')">
      <div class="card-head">
        <span class="card-sym" style="color:#059669;">I</span>
        <span class="card-title">Interest</span>
      </div>
      <div class="card-desc">Fee earned or paid for using money</div>
      <div class="card-rule">Total dollar gain/cost</div>
      <div class="card-example">
        <span class="ex-label">Output</span>
        <span class="ex-val">$150</span>
      </div>
    </div>

    
    <div class="detail-card card-p active" data-var="p" onclick="selectVar('p')">
      <div class="card-head">
        <span class="card-sym" style="color:#2563eb;">P</span>
        <span class="card-title">Principal</span>
      </div>
      <div class="card-desc">Initial starting balance</div>
      <div class="card-rule">Base money amount</div>
      <div class="card-example">
        <span class="ex-label">Input</span>
        <span class="ex-val">$1,000</span>
      </div>
    </div>

    
    <div class="detail-card card-r active" data-var="r" onclick="selectVar('r')">
      <div class="card-head">
        <span class="card-sym" style="color:#4f46e5;">r</span>
        <span class="card-title">Annual Rate</span>
      </div>
      <div class="card-desc">Percent charged per year</div>
      <div class="card-rule">5% → 0.05 (decimal)</div>
      <div class="card-example">
        <span class="ex-label">Input</span>
        <span class="ex-val">0.05</span>
      </div>
    </div>

    
    <div class="detail-card card-t active" data-var="t" onclick="selectVar('t')">
      <div class="card-head">
        <span class="card-sym" style="color:#d97706;">t</span>
        <span class="card-title">Time</span>
      </div>
      <div class="card-desc">Duration of investment</div>
      <div class="card-rule">Must be in years</div>
      <div class="card-example">
        <span class="ex-label">Input</span>
        <span class="ex-val">3 yrs</span>
      </div>
    </div>
  </div>

  
  <div class="example-banner">
    <div class="calc-part var-p active" data-var="p" onclick="selectVar('p')" title="Principal: $1,000">
      $1,000 <span class="sub">(P)</span>
    </div>
    <span class="eq-op">×</span>
    <div class="calc-part var-r active" data-var="r" onclick="selectVar('r')" title="Rate: 5% = 0.05">
      0.05 <span class="sub">(r)</span>
    </div>
    <span class="eq-op">×</span>
    <div class="calc-part var-t active" data-var="t" onclick="selectVar('t')" title="Time: 3 Years">
      3 <span class="sub">(t)</span>
    </div>
    <span class="eq-op">=</span>
    <div class="calc-part var-i active" data-var="i" onclick="selectVar('i')" title="Interest: $150">
      $150 <span class="sub">(I)</span>
    </div>
  </div>

  <script>
    let activeVar = null;

    function selectVar(v) {
      if (activeVar === v) {
        // Toggle back to showing all
        activeVar = null;
      } else {
        activeVar = v;
      }
      updateUI();
    }

    function updateUI() {
      const allElements = document.querySelectorAll('[data-var]');
      
      allElements.forEach(el => {
        const elVar = el.getAttribute('data-var');
        if (!activeVar) {
          el.classList.add('active');
          el.classList.remove('dimmed');
        } else if (elVar === activeVar) {
          el.classList.add('active');
          el.classList.remove('dimmed');
        } else {
          el.classList.remove('active');
          el.classList.add('dimmed');
        }
      });
    }
  </script>
</body>
</html>

OGM.9.MEAS.4

Aligned learning resources

Related diagrams