Accessible Color Token System

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

/* ══════════════════════════════════════
   DARK THEME TOKENS (default)
   ══════════════════════════════════════ */
:root {
  color-scheme: dark;

  /* Text */
  --color-text-primary: #e5e5e5;
  --color-text-secondary: #a3a3a3;
  --color-text-muted: #737373;
  --color-text-inverse: #0a0a0a;

  /* Backgrounds */
  --color-bg-base: #0a0a0a;
  --color-bg-surface: #141414;
  --color-bg-elevated: #1a1a1a;
  --color-bg-overlay: #262626;

  /* Borders */
  --color-border-default: #262626;
  --color-border-strong: #404040;

  /* Accent */
  --color-accent: #3b82f6;
  --color-accent-text: #ffffff;

  /* States */
  --color-success: #4ade80;
  --color-warning: #fbbf24;
  --color-error: #f87171;
  --color-info: #60a5fa;

  --transition: 0.3s;
}

/* ══════════════════════════════════════
   LIGHT THEME TOKENS
   ══════════════════════════════════════ */
.light {
  color-scheme: light;

  --color-text-primary: #111111;
  --color-text-secondary: #525252;
  --color-text-muted: #737373;
  --color-text-inverse: #ffffff;

  --color-bg-base: #ffffff;
  --color-bg-surface: #f5f5f5;
  --color-bg-elevated: #fafafa;
  --color-bg-overlay: #e5e5e5;

  --color-border-default: #e5e5e5;
  --color-border-strong: #d4d4d4;

  --color-accent: #2563eb;
  --color-accent-text: #ffffff;

  --color-success: #16a34a;
  --color-warning: #d97706;
  --color-error: #dc2626;
  --color-info: #2563eb;
}

/* ── Base ── */
body {
  font-family: Inter, system-ui, -apple-system, sans-serif;
  background: var(--color-bg-base);
  color: var(--color-text-primary);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  padding: 2rem;
  transition: background var(--transition), color var(--transition);
}

.page {
  width: 100%;
  max-width: 840px;
}

/* ── Header ── */
.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--color-border-default);
}

.header-title {
  font-size: 1.5rem;
  font-weight: 800;
  letter-spacing: -0.02em;
}
.header-sub {
  color: var(--color-text-muted);
  font-size: 0.8125rem;
  margin-top: 0.25rem;
}

.theme-btn {
  display: flex;
  align-items: center;
  gap: 0.375rem;
  background: var(--color-bg-surface);
  border: 1px solid var(--color-border-default);
  border-radius: 0.5rem;
  color: var(--color-text-primary);
  padding: 0.5rem 0.75rem;
  font-size: 0.75rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s;
}

.theme-btn:hover {
  background: var(--color-bg-elevated);
}

.icon-sun {
  display: none;
}
.icon-moon {
  display: block;
}
.light .icon-sun {
  display: block;
}
.light .icon-moon {
  display: none;
}

/* ── Sections ── */
.section {
  margin-bottom: 2.5rem;
}
.section-title {
  font-size: 1.125rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
}
.section-desc {
  color: var(--color-text-secondary);
  font-size: 0.8125rem;
  margin-bottom: 1rem;
  line-height: 1.5;
}

/* ── Token grid ── */
.token-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

.token-category {
  background: var(--color-bg-surface);
  border: 1px solid var(--color-border-default);
  border-radius: 0.75rem;
  padding: 1rem;
  transition: background var(--transition), border-color var(--transition);
}

.token-cat-title {
  font-size: 0.6875rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
  margin-bottom: 0.75rem;
}

.token-row {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.375rem 0;
  border-bottom: 1px solid var(--color-border-default);
}

.token-row:last-child {
  border-bottom: none;
}

.token-swatch {
  width: 20px;
  height: 20px;
  border-radius: 0.25rem;
  border: 1px solid var(--color-border-strong);
  flex-shrink: 0;
}

.token-row code {
  flex: 1;
  font-family: "SF Mono", "Fira Code", monospace;
  font-size: 0.6875rem;
  color: var(--color-text-secondary);
}

.token-value {
  font-family: "SF Mono", "Fira Code", monospace;
  font-size: 0.625rem;
  color: var(--color-text-muted);
}

/* ── Sample components ── */
.sample-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.sample-card {
  background: var(--color-bg-surface);
  border: 1px solid var(--color-border-default);
  border-radius: 0.75rem;
  padding: 1.25rem;
  transition: background var(--transition), border-color var(--transition);
}

.sample-card.elevated {
  background: var(--color-bg-elevated);
}

.sample-card-title {
  font-size: 0.9375rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  color: var(--color-text-primary);
}
.sample-card-body {
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
  line-height: 1.5;
  margin-bottom: 1rem;
}
.sample-card-body code {
  font-size: 0.6875rem;
  background: var(--color-bg-overlay);
  padding: 0.125rem 0.25rem;
  border-radius: 0.25rem;
}

.sample-btn-primary {
  background: var(--color-accent);
  color: var(--color-accent-text);
  border: none;
  border-radius: 0.375rem;
  padding: 0.5rem 1rem;
  font-size: 0.8125rem;
  font-weight: 600;
  cursor: pointer;
}

.sample-btn-outline {
  background: transparent;
  color: var(--color-accent);
  border: 1px solid var(--color-accent);
  border-radius: 0.375rem;
  padding: 0.5rem 1rem;
  font-size: 0.8125rem;
  font-weight: 600;
  cursor: pointer;
}

/* ── Sample alerts ── */
.sample-alerts {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.5rem;
}

.sample-alert {
  padding: 0.75rem 1rem;
  border-radius: 0.5rem;
  font-size: 0.8125rem;
  line-height: 1.5;
  border-left: 3px solid;
  background: var(--color-bg-surface);
  color: var(--color-text-secondary);
  transition: background var(--transition);
}

.sample-alert.success {
  border-left-color: var(--color-success);
}
.sample-alert.warning {
  border-left-color: var(--color-warning);
}
.sample-alert.error {
  border-left-color: var(--color-error);
}
.sample-alert.info {
  border-left-color: var(--color-info);
}

.sample-alert.success strong {
  color: var(--color-success);
}
.sample-alert.warning strong {
  color: var(--color-warning);
}
.sample-alert.error strong {
  color: var(--color-error);
}
.sample-alert.info strong {
  color: var(--color-info);
}

/* ── Contrast matrix ── */
.matrix-wrap {
  overflow-x: auto;
}

.matrix {
  border-collapse: collapse;
  font-size: 0.6875rem;
  width: 100%;
  min-width: 500px;
}

.matrix th,
.matrix td {
  padding: 0.375rem 0.5rem;
  border: 1px solid var(--color-border-default);
  text-align: center;
  white-space: nowrap;
}

.matrix th {
  background: var(--color-bg-surface);
  font-weight: 600;
  color: var(--color-text-secondary);
  font-size: 0.5625rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.matrix th:first-child {
  text-align: left;
}
.matrix td:first-child {
  text-align: left;
  font-weight: 600;
  background: var(--color-bg-surface);
  color: var(--color-text-secondary);
  font-size: 0.5625rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.matrix .cell-aaa {
  background: #052e16;
  color: #4ade80;
  font-weight: 700;
}
.matrix .cell-aa {
  background: #422006;
  color: #fbbf24;
  font-weight: 700;
}
.matrix .cell-fail {
  background: #1a0a0a;
  color: #737373;
}

.light .matrix .cell-aaa {
  background: #dcfce7;
  color: #15803d;
}
.light .matrix .cell-aa {
  background: #fef3c7;
  color: #92400e;
}
.light .matrix .cell-fail {
  background: #fef2f2;
  color: #a3a3a3;
}

@media (max-width: 640px) {
  .token-grid {
    grid-template-columns: 1fr;
  }
  .sample-grid {
    grid-template-columns: 1fr;
  }
  .sample-alerts {
    grid-template-columns: 1fr;
  }
}

(function () {
  var toggleBtn = document.getElementById("theme-toggle");
  var themeLabel = document.getElementById("theme-label");
  var body = document.body;

  // ── Token values for each theme ──
  var tokens = {
    dark: {
      "--color-text-primary": "#e5e5e5",
      "--color-text-secondary": "#a3a3a3",
      "--color-text-muted": "#737373",
      "--color-text-inverse": "#0a0a0a",
      "--color-bg-base": "#0a0a0a",
      "--color-bg-surface": "#141414",
      "--color-bg-elevated": "#1a1a1a",
      "--color-bg-overlay": "#262626",
      "--color-border-default": "#262626",
      "--color-border-strong": "#404040",
      "--color-accent": "#3b82f6",
      "--color-accent-text": "#ffffff",
      "--color-success": "#4ade80",
      "--color-warning": "#fbbf24",
      "--color-error": "#f87171",
      "--color-info": "#60a5fa",
    },
    light: {
      "--color-text-primary": "#111111",
      "--color-text-secondary": "#525252",
      "--color-text-muted": "#737373",
      "--color-text-inverse": "#ffffff",
      "--color-bg-base": "#ffffff",
      "--color-bg-surface": "#f5f5f5",
      "--color-bg-elevated": "#fafafa",
      "--color-bg-overlay": "#e5e5e5",
      "--color-border-default": "#e5e5e5",
      "--color-border-strong": "#d4d4d4",
      "--color-accent": "#2563eb",
      "--color-accent-text": "#ffffff",
      "--color-success": "#16a34a",
      "--color-warning": "#d97706",
      "--color-error": "#dc2626",
      "--color-info": "#2563eb",
    },
  };

  var textTokens = [
    "--color-text-primary",
    "--color-text-secondary",
    "--color-text-muted",
    "--color-text-inverse",
    "--color-accent",
    "--color-success",
    "--color-warning",
    "--color-error",
    "--color-info",
  ];

  var bgTokens = [
    "--color-bg-base",
    "--color-bg-surface",
    "--color-bg-elevated",
    "--color-bg-overlay",
  ];

  var currentTheme = "dark";

  // ── WCAG helpers ──
  function hexToRgb(hex) {
    hex = hex.replace("#", "");
    if (hex.length === 3) hex = hex[0] + hex[0] + hex[1] + hex[1] + hex[2] + hex[2];
    var n = parseInt(hex, 16);
    return [(n >> 16) & 255, (n >> 8) & 255, n & 255];
  }

  function linearize(c) {
    var s = c / 255;
    return s <= 0.04045 ? s / 12.92 : Math.pow((s + 0.055) / 1.055, 2.4);
  }

  function luminance(rgb) {
    return 0.2126 * linearize(rgb[0]) + 0.7152 * linearize(rgb[1]) + 0.0722 * linearize(rgb[2]);
  }

  function contrastRatio(hex1, hex2) {
    var l1 = luminance(hexToRgb(hex1));
    var l2 = luminance(hexToRgb(hex2));
    return (Math.max(l1, l2) + 0.05) / (Math.min(l1, l2) + 0.05);
  }

  function shortName(token) {
    return token.replace("--color-", "");
  }

  // ── Update token swatches ──
  function updateSwatches() {
    var t = tokens[currentTheme];
    var rows = document.querySelectorAll(".token-row[data-token]");
    rows.forEach(function (row) {
      var name = row.getAttribute("data-token");
      var val = t[name];
      if (!val) return;
      row.querySelector(".token-swatch").style.background = val;
      row.querySelector(".token-value").textContent = val;
    });
  }

  // ── Build contrast matrix ──
  function buildMatrix() {
    var t = tokens[currentTheme];
    var thead = document.getElementById("matrix-head");
    var tbody = document.getElementById("matrix-body");

    // Header row
    var headerHtml = "<tr><th></th>";
    bgTokens.forEach(function (bg) {
      headerHtml += "<th>" + shortName(bg) + "</th>";
    });
    headerHtml += "</tr>";
    thead.innerHTML = headerHtml;

    // Body rows
    tbody.innerHTML = "";
    textTokens.forEach(function (fg) {
      var tr = document.createElement("tr");
      var rowHtml = "<td>" + shortName(fg) + "</td>";

      bgTokens.forEach(function (bg) {
        var ratio = contrastRatio(t[fg], t[bg]);
        var cls, label;
        if (ratio >= 7) {
          cls = "cell-aaa";
          label = ratio.toFixed(1) + " AAA";
        } else if (ratio >= 4.5) {
          cls = "cell-aa";
          label = ratio.toFixed(1) + " AA";
        } else {
          cls = "cell-fail";
          label = ratio.toFixed(1);
        }
        rowHtml += '<td class="' + cls + '">' + label + "</td>";
      });

      tr.innerHTML = rowHtml;
      tbody.appendChild(tr);
    });
  }

  // ── Apply theme ──
  function applyTheme(theme) {
    currentTheme = theme;
    if (theme === "light") {
      body.classList.add("light");
    } else {
      body.classList.remove("light");
    }
    themeLabel.textContent = theme === "light" ? "Dark" : "Light";
    updateSwatches();
    buildMatrix();
  }

  // ── Events ──
  toggleBtn.addEventListener("click", function () {
    applyTheme(currentTheme === "dark" ? "light" : "dark");
  });

  // ── Init ──
  applyTheme("dark");
})();

<!doctype html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>Accessible Color Token System</title>
  <link rel="stylesheet" href="style.css" />
</head>
<body>
  <div class="page">
    <header class="header">
      <div>
        <h1 class="header-title">Color Token System</h1>
        <p class="header-sub">Semantic design tokens with guaranteed WCAG contrast compliance.</p>
      </div>
      <button class="theme-btn" id="theme-toggle" aria-label="Toggle dark/light theme">
        <svg class="icon-sun" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><circle cx="12" cy="12" r="5"/><line x1="12" y1="1" x2="12" y2="3"/><line x1="12" y1="21" x2="12" y2="23"/><line x1="4.22" y1="4.22" x2="5.64" y2="5.64"/><line x1="18.36" y1="18.36" x2="19.78" y2="19.78"/><line x1="1" y1="12" x2="3" y2="12"/><line x1="21" y1="12" x2="23" y2="12"/><line x1="4.22" y1="19.78" x2="5.64" y2="18.36"/><line x1="18.36" y1="5.64" x2="19.78" y2="4.22"/></svg>
        <svg class="icon-moon" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><path d="M21 12.79A9 9 0 1 1 11.21 3 7 7 0 0 0 21 12.79z"/></svg>
        <span id="theme-label">Light</span>
      </button>
    </header>

    <!-- Token reference -->
    <section class="section">
      <h2 class="section-title">Token Reference</h2>
      <div class="token-grid" id="token-grid">
        <!-- Text tokens -->
        <div class="token-category">
          <h3 class="token-cat-title">Text</h3>
          <div class="token-row" data-token="--color-text-primary">
            <span class="token-swatch"></span>
            <code>--color-text-primary</code>
            <span class="token-value"></span>
          </div>
          <div class="token-row" data-token="--color-text-secondary">
            <span class="token-swatch"></span>
            <code>--color-text-secondary</code>
            <span class="token-value"></span>
          </div>
          <div class="token-row" data-token="--color-text-muted">
            <span class="token-swatch"></span>
            <code>--color-text-muted</code>
            <span class="token-value"></span>
          </div>
          <div class="token-row" data-token="--color-text-inverse">
            <span class="token-swatch"></span>
            <code>--color-text-inverse</code>
            <span class="token-value"></span>
          </div>
        </div>

        <!-- Background tokens -->
        <div class="token-category">
          <h3 class="token-cat-title">Backgrounds</h3>
          <div class="token-row" data-token="--color-bg-base">
            <span class="token-swatch"></span>
            <code>--color-bg-base</code>
            <span class="token-value"></span>
          </div>
          <div class="token-row" data-token="--color-bg-surface">
            <span class="token-swatch"></span>
            <code>--color-bg-surface</code>
            <span class="token-value"></span>
          </div>
          <div class="token-row" data-token="--color-bg-elevated">
            <span class="token-swatch"></span>
            <code>--color-bg-elevated</code>
            <span class="token-value"></span>
          </div>
          <div class="token-row" data-token="--color-bg-overlay">
            <span class="token-swatch"></span>
            <code>--color-bg-overlay</code>
            <span class="token-value"></span>
          </div>
        </div>

        <!-- Border & accent tokens -->
        <div class="token-category">
          <h3 class="token-cat-title">Borders &amp; Accents</h3>
          <div class="token-row" data-token="--color-border-default">
            <span class="token-swatch"></span>
            <code>--color-border-default</code>
            <span class="token-value"></span>
          </div>
          <div class="token-row" data-token="--color-border-strong">
            <span class="token-swatch"></span>
            <code>--color-border-strong</code>
            <span class="token-value"></span>
          </div>
          <div class="token-row" data-token="--color-accent">
            <span class="token-swatch"></span>
            <code>--color-accent</code>
            <span class="token-value"></span>
          </div>
          <div class="token-row" data-token="--color-accent-text">
            <span class="token-swatch"></span>
            <code>--color-accent-text</code>
            <span class="token-value"></span>
          </div>
        </div>

        <!-- State tokens -->
        <div class="token-category">
          <h3 class="token-cat-title">States</h3>
          <div class="token-row" data-token="--color-success">
            <span class="token-swatch"></span>
            <code>--color-success</code>
            <span class="token-value"></span>
          </div>
          <div class="token-row" data-token="--color-warning">
            <span class="token-swatch"></span>
            <code>--color-warning</code>
            <span class="token-value"></span>
          </div>
          <div class="token-row" data-token="--color-error">
            <span class="token-swatch"></span>
            <code>--color-error</code>
            <span class="token-value"></span>
          </div>
          <div class="token-row" data-token="--color-info">
            <span class="token-swatch"></span>
            <code>--color-info</code>
            <span class="token-value"></span>
          </div>
        </div>
      </div>
    </section>

    <!-- Sample components -->
    <section class="section">
      <h2 class="section-title">Components Using Tokens</h2>
      <div class="sample-grid">
        <div class="sample-card">
          <h3 class="sample-card-title">Surface Card</h3>
          <p class="sample-card-body">This card uses <code>--color-bg-surface</code> as background and <code>--color-text-primary</code> for heading text. The body uses <code>--color-text-secondary</code>.</p>
          <button class="sample-btn-primary">Primary Action</button>
        </div>
        <div class="sample-card elevated">
          <h3 class="sample-card-title">Elevated Card</h3>
          <p class="sample-card-body">Elevated surface using <code>--color-bg-elevated</code>. Borders use <code>--color-border-default</code>. Button uses <code>--color-accent</code>.</p>
          <button class="sample-btn-outline">Outline Action</button>
        </div>
      </div>

      <!-- Alerts -->
      <div class="sample-alerts">
        <div class="sample-alert success">
          <strong>Success:</strong> Changes saved successfully.
        </div>
        <div class="sample-alert warning">
          <strong>Warning:</strong> API rate limit at 85%.
        </div>
        <div class="sample-alert error">
          <strong>Error:</strong> Unable to connect to database.
        </div>
        <div class="sample-alert info">
          <strong>Info:</strong> New version available (v2.4.0).
        </div>
      </div>
    </section>

    <!-- Contrast matrix -->
    <section class="section">
      <h2 class="section-title">Contrast Matrix</h2>
      <p class="section-desc">Shows which text/background token pairs meet WCAG AA (4.5:1) and AAA (7:1).</p>
      <div class="matrix-wrap">
        <table class="matrix" id="contrast-matrix" aria-label="Contrast compliance matrix">
          <thead id="matrix-head"></thead>
          <tbody id="matrix-body"></tbody>
        </table>
      </div>
    </section>
  </div>
  <script src="script.js"></script>
</body>
</html>