Accessible Palette Generator

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

body {
  font-family: Inter, system-ui, -apple-system, sans-serif;
  background: #0a0a0a;
  color: #e5e5e5;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2rem;
}

.generator {
  width: 100%;
  max-width: 640px;
}

.gen-title {
  font-size: 1.75rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 0.375rem;
}

.gen-sub {
  color: #737373;
  font-size: 0.875rem;
  line-height: 1.5;
  margin-bottom: 2rem;
}

/* ── Base input ── */
.base-input {
  margin-bottom: 2rem;
}

.base-input label {
  display: block;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: #a3a3a3;
  margin-bottom: 0.5rem;
}

.base-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.base-row input[type="color"] {
  width: 36px;
  height: 36px;
  border: none;
  border-radius: 0.375rem;
  cursor: pointer;
  padding: 0;
  background: none;
  -webkit-appearance: none;
}

.base-row input[type="color"]::-webkit-color-swatch-wrapper {
  padding: 0;
}
.base-row input[type="color"]::-webkit-color-swatch {
  border: 1px solid #404040;
  border-radius: 0.375rem;
}

.base-row input[type="text"] {
  background: #171717;
  border: 1px solid #262626;
  border-radius: 0.5rem;
  color: #e5e5e5;
  font-family: "SF Mono", "Fira Code", monospace;
  font-size: 0.875rem;
  padding: 0.5rem 0.75rem;
  width: 110px;
  outline: none;
}

.base-row input[type="text"]:focus {
  border-color: #525252;
}

.randomize-btn {
  display: flex;
  align-items: center;
  gap: 0.375rem;
  background: #171717;
  border: 1px solid #262626;
  border-radius: 0.5rem;
  color: #a3a3a3;
  font-size: 0.8125rem;
  font-weight: 500;
  padding: 0.5rem 0.875rem;
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
}

.randomize-btn:hover {
  background: #262626;
  color: #e5e5e5;
}

/* ── Palette ── */
.palette {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 0.5rem;
  margin-bottom: 1.5rem;
}

.swatch {
  border-radius: 0.75rem;
  border: 1px solid #262626;
  overflow: hidden;
  background: #171717;
}

.swatch-color {
  height: 80px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8125rem;
  font-weight: 600;
  position: relative;
}

.swatch-color span {
  font-family: "SF Mono", "Fira Code", monospace;
  font-size: 0.6875rem;
  opacity: 0.85;
}

.swatch-info {
  padding: 0.5rem;
  font-size: 0.6875rem;
}

.swatch-hex {
  font-family: "SF Mono", "Fira Code", monospace;
  color: #a3a3a3;
  margin-bottom: 0.375rem;
}

.swatch-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.25rem;
}

.swatch-row .label {
  color: #737373;
}

.swatch-row .ratio {
  font-weight: 600;
  font-family: "SF Mono", "Fira Code", monospace;
}

.badge {
  font-size: 0.5625rem;
  font-weight: 700;
  padding: 0.0625rem 0.3125rem;
  border-radius: 0.1875rem;
  letter-spacing: 0.04em;
}

.badge-aaa {
  background: #14532d;
  color: #4ade80;
}
.badge-aa {
  background: #422006;
  color: #fbbf24;
}
.badge-fail {
  background: #450a0a;
  color: #f87171;
}

/* ── Actions ── */
.actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}

.copy-btn {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  background: #e5e5e5;
  color: #0a0a0a;
  border: none;
  border-radius: 0.5rem;
  padding: 0.625rem 1rem;
  font-size: 0.8125rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s;
}

.copy-btn:hover {
  background: #d4d4d4;
}

.copy-toast {
  font-size: 0.8125rem;
  color: #22c55e;
  font-weight: 600;
  opacity: 0;
  transition: opacity 0.3s;
}

.copy-toast.show {
  opacity: 1;
}

/* ── Legend ── */
.legend {
  display: flex;
  gap: 1.25rem;
  flex-wrap: wrap;
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 0.375rem;
  font-size: 0.75rem;
  color: #737373;
}

@media (max-width: 640px) {
  .palette {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 400px) {
  .palette {
    grid-template-columns: repeat(2, 1fr);
  }
}

(function () {
  var basePicker = document.getElementById("base-picker");
  var baseInput = document.getElementById("base-color");
  var randomBtn = document.getElementById("randomize-btn");
  var paletteEl = document.getElementById("palette");
  var copyBtn = document.getElementById("copy-css");
  var copyToast = document.getElementById("copy-toast");

  var currentPalette = [];

  // ── Color math ──
  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 rgbToHex(r, g, b) {
    return (
      "#" +
      [r, g, b]
        .map(function (c) {
          var h = Math.round(Math.max(0, Math.min(255, c))).toString(16);
          return h.length === 1 ? "0" + h : h;
        })
        .join("")
    );
  }

  function rgbToHsl(r, g, b) {
    r /= 255;
    g /= 255;
    b /= 255;
    var max = Math.max(r, g, b),
      min = Math.min(r, g, b);
    var h,
      s,
      l = (max + min) / 2;
    if (max === min) {
      h = s = 0;
    } else {
      var d = max - min;
      s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
      if (max === r) h = ((g - b) / d + (g < b ? 6 : 0)) / 6;
      else if (max === g) h = ((b - r) / d + 2) / 6;
      else h = ((r - g) / d + 4) / 6;
    }
    return [h * 360, s * 100, l * 100];
  }

  function hslToRgb(h, s, l) {
    h /= 360;
    s /= 100;
    l /= 100;
    var r, g, b;
    if (s === 0) {
      r = g = b = l;
    } else {
      function hue2rgb(p, q, t) {
        if (t < 0) t += 1;
        if (t > 1) t -= 1;
        if (t < 1 / 6) return p + (q - p) * 6 * t;
        if (t < 1 / 2) return q;
        if (t < 2 / 3) return p + (q - p) * (2 / 3 - t) * 6;
        return p;
      }
      var q = l < 0.5 ? l * (1 + s) : l + s - l * s;
      var p = 2 * l - q;
      r = hue2rgb(p, q, h + 1 / 3);
      g = hue2rgb(p, q, h);
      b = hue2rgb(p, q, h - 1 / 3);
    }
    return [Math.round(r * 255), Math.round(g * 255), Math.round(b * 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);
  }

  // ── Generate palette ──
  function generatePalette(baseHex) {
    var rgb = hexToRgb(baseHex);
    var hsl = rgbToHsl(rgb[0], rgb[1], rgb[2]);
    var hue = hsl[0];
    var sat = hsl[1];

    // 7 lightness stops
    var stops = [95, 85, 70, 50, 35, 22, 10];
    var palette = stops.map(function (l, i) {
      // Slightly adjust saturation for extreme lightness
      var adjustedSat = l > 85 ? sat * 0.4 : l < 20 ? sat * 0.6 : sat;
      var c = hslToRgb(hue, adjustedSat, l);
      var hex = rgbToHex(c[0], c[1], c[2]);
      return { hex: hex, lightness: l, index: (i + 1) * 100 };
    });
    return palette;
  }

  function getBadge(ratio) {
    if (ratio >= 7) return { cls: "badge-aaa", text: "AAA" };
    if (ratio >= 4.5) return { cls: "badge-aa", text: "AA" };
    return { cls: "badge-fail", text: "Fail" };
  }

  // ── Render ──
  function render() {
    var baseHex = baseInput.value;
    if (!/^#([0-9a-fA-F]{3}|[0-9a-fA-F]{6})$/.test(baseHex)) return;

    currentPalette = generatePalette(baseHex);
    paletteEl.innerHTML = "";

    currentPalette.forEach(function (swatch) {
      var whiteRatio = contrastRatio(swatch.hex, "#ffffff");
      var darkRatio = contrastRatio(swatch.hex, "#111111");
      var whiteBadge = getBadge(whiteRatio);
      var darkBadge = getBadge(darkRatio);

      // Choose text color for the swatch preview
      var textColor = swatch.lightness > 55 ? "#111111" : "#ffffff";

      var el = document.createElement("div");
      el.className = "swatch";
      el.innerHTML =
        '<div class="swatch-color" style="background:' +
        swatch.hex +
        ";color:" +
        textColor +
        '">' +
        "<span>" +
        swatch.index +
        "</span>" +
        "</div>" +
        '<div class="swatch-info">' +
        '<div class="swatch-hex">' +
        swatch.hex +
        "</div>" +
        '<div class="swatch-row">' +
        '<span class="label" style="color:#fff">\u25CF White</span>' +
        '<span class="badge ' +
        whiteBadge.cls +
        '">' +
        whiteBadge.text +
        " " +
        whiteRatio.toFixed(1) +
        "</span>" +
        "</div>" +
        '<div class="swatch-row">' +
        '<span class="label">\u25CF Dark</span>' +
        '<span class="badge ' +
        darkBadge.cls +
        '">' +
        darkBadge.text +
        " " +
        darkRatio.toFixed(1) +
        "</span>" +
        "</div>" +
        "</div>";
      paletteEl.appendChild(el);
    });
  }

  // ── Copy CSS ──
  function copyCss() {
    var lines = [":root {"];
    currentPalette.forEach(function (s) {
      lines.push("  --color-" + s.index + ": " + s.hex + ";");
    });
    lines.push("}");
    navigator.clipboard.writeText(lines.join("\n")).then(function () {
      copyToast.classList.add("show");
      setTimeout(function () {
        copyToast.classList.remove("show");
      }, 1500);
    });
  }

  // ── Events ──
  basePicker.addEventListener("input", function () {
    baseInput.value = basePicker.value;
    render();
  });

  baseInput.addEventListener("input", function () {
    if (/^#([0-9a-fA-F]{6})$/.test(baseInput.value)) {
      basePicker.value = baseInput.value;
    }
    render();
  });

  randomBtn.addEventListener("click", function () {
    var h = Math.floor(Math.random() * 360);
    var s = 50 + Math.floor(Math.random() * 40);
    var l = 40 + Math.floor(Math.random() * 20);
    var rgb = hslToRgb(h, s, l);
    var hex = rgbToHex(rgb[0], rgb[1], rgb[2]);
    baseInput.value = hex;
    basePicker.value = hex;
    render();
  });

  copyBtn.addEventListener("click", copyCss);

  // ── Init ──
  render();
})();

<!doctype html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>Accessible Palette Generator</title>
  <link rel="stylesheet" href="style.css" />
</head>
<body>
  <div class="generator">
    <h1 class="gen-title">Accessible Palette Generator</h1>
    <p class="gen-sub">Generate palettes that meet WCAG 2.1 contrast requirements automatically.</p>

    <!-- Base color input -->
    <div class="base-input">
      <label for="base-color">Base Color</label>
      <div class="base-row">
        <input type="color" id="base-picker" value="#3b82f6" aria-label="Pick base color" />
        <input type="text" id="base-color" value="#3b82f6" maxlength="7" spellcheck="false" />
        <button class="randomize-btn" id="randomize-btn" aria-label="Random color">
          <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M21 16V8a2 2 0 0 0-1-1.73l-7-4a2 2 0 0 0-2 0l-7 4A2 2 0 0 0 3 8v8a2 2 0 0 0 1 1.73l7 4a2 2 0 0 0 2 0l7-4A2 2 0 0 0 21 16z"/><circle cx="12" cy="12" r="2"/></svg>
          Randomize
        </button>
      </div>
    </div>

    <!-- Palette -->
    <div class="palette" id="palette"></div>

    <!-- Copy actions -->
    <div class="actions">
      <button class="copy-btn" id="copy-css" aria-label="Copy CSS variables">
        <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><rect x="9" y="9" width="13" height="13" rx="2"/><path d="M5 15H4a2 2 0 0 1-2-2V4a2 2 0 0 1 2-2h9a2 2 0 0 1 2 2v1"/></svg>
        Copy CSS Variables
      </button>
      <span class="copy-toast" id="copy-toast">Copied!</span>
    </div>

    <!-- Legend -->
    <div class="legend">
      <div class="legend-item"><span class="badge badge-aaa">AAA</span> Contrast &ge; 7:1</div>
      <div class="legend-item"><span class="badge badge-aa">AA</span> Contrast &ge; 4.5:1</div>
      <div class="legend-item"><span class="badge badge-fail">Fail</span> Below 4.5:1</div>
    </div>
  </div>
  <script src="script.js"></script>
</body>
</html>