/* ========================================
       CSS VARIABLES & RESET
       ======================================== */
    :root {
      --bg-primary: #020617;
      --bg-secondary: #0f172a;
      --bg-tertiary: #1e293b;
      --text-primary: #e5e7eb;
      --text-secondary: #9ca3af;
      --text-muted: #6b7280;
      --accent-primary: #38bdf8;
      --accent-secondary: #22d3ee;
      --accent-hover: #0ea5e9;
      --success: #22c55e;
      --warning: #f59e0b;
      --danger: #ef4444;
      --border-color: rgba(148, 163, 184, 0.3);
      --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.4);
      --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.5);
      --shadow-lg: 0 20px 45px rgba(15, 23, 42, 0.95);
      --radius-sm: 8px;
      --radius-md: 12px;
      --radius-lg: 16px;
      --transition: all 0.2s ease;
      --max-width: 1200px;
      --container-padding: 24px;
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    }

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

    html, body {
      height: 100%;
      background: var(--bg-primary);
      color: var(--text-primary);
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }

    /* ========================================
       TECHNICAL BACKGROUND LAYERS
       ======================================== */
    body::before,
    body::after {
      content: "";
      position: fixed;
      inset: 0;
      z-index: -2;
      pointer-events: none;
    }

    /* Gradient base layer */
    body::before {
      background:
        radial-gradient(circle at 0% 0%, rgba(56, 189, 248, 0.16) 0, transparent 55%),
        radial-gradient(circle at 100% 100%, rgba(129, 140, 248, 0.2) 0, transparent 55%),
        radial-gradient(circle at 0% 100%, rgba(45, 212, 191, 0.18) 0, transparent 55%),
        var(--bg-primary);
    }

    /* Grid overlay with tech lines */
    body::after {
      opacity: 0.18;
      background-image:
        linear-gradient(to right, rgba(148, 163, 184, 0.18) 1px, transparent 1px),
        linear-gradient(to bottom, rgba(148, 163, 184, 0.18) 1px, transparent 1px),
        linear-gradient(135deg, rgba(56, 189, 248, 0.28) 0, transparent 55%),
        linear-gradient(225deg, rgba(45, 212, 191, 0.18) 0, transparent 55%);
      background-size:
        32px 32px,
        32px 32px,
        380px 380px,
        420px 420px;
      mix-blend-mode: screen;
    }

    /* ========================================
       HEADER STYLES
       ======================================== */
    header {
      background: rgba(15, 23, 42, 0.96);
      padding: 20px 0;
      box-shadow: var(--shadow-md);
      backdrop-filter: blur(12px);
      border-bottom: 1px solid var(--border-color);
      position: sticky;
      top: 0;
      z-index: 100;
    }

    .header-container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 var(--container-padding);
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 20px;
    }

    .logo {
      display: flex;
      align-items: center;
      gap: 14px;
      text-decoration: none;
      color: inherit;
    }

    .logo img {
      height: 56px;
      width: auto;
      border-radius: var(--radius-md);
      box-shadow: 0 0 0 2px rgba(15, 23, 42, 0.8);
    }

    .logo-text h1 {
      font-size: 1.3rem;
      font-weight: 800;
      letter-spacing: 0.3px;
      margin: 0;
    }

    .logo-text p {
      font-size: 0.85rem;
      color: var(--text-secondary);
      margin: 2px 0 0;
    }

    .nav {
      display: flex;
      gap: 12px;
      align-items: center;
    }

    .nav a {
      color: #c7d2fe;
      text-decoration: none;
      font-weight: 600;
      font-size: 0.95rem;
      padding: 8px 14px;
      border-radius: 999px;
      transition: var(--transition);
    }

    .nav a:hover {
      background: rgba(56, 189, 248, 0.12);
      color: #e0f2fe;
      transform: translateY(-1px);
    }

    /* ========================================
       MAIN CONTENT STYLES
       ======================================== */
    main {
      max-width: var(--max-width);
      margin: 40px auto;
      padding: 0 var(--container-padding);
      min-height: calc(100vh - 300px);
    }

    .page-title {
      text-align: center;
      margin-bottom: 16px;
    }

    .page-title h2 {
      font-size: 2.5rem;
      background: linear-gradient(135deg, #22d3ee, #a855f7);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      background-clip: text;
      margin-bottom: 12px;
    }

    .page-title p {
      color: var(--text-secondary);
      font-size: 1.05rem;
      max-width: 600px;
      margin: 0 auto;
      line-height: 1.6;
    }

    /* ========================================
       COLOR PICKER CARD
       ======================================== */
    .picker-card {
      position: relative;
      background: radial-gradient(circle at 0% 0%, rgba(56, 189, 248, 0.22) 0, transparent 60%),
                  radial-gradient(circle at 100% 100%, rgba(129, 140, 248, 0.18) 0, transparent 65%),
                  rgba(15, 23, 42, 0.96);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-lg), 0 0 0 1px var(--border-color);
      padding: 40px;
      margin-top: 32px;
      overflow: hidden;
    }

    .picker-card::before {
      content: "";
      position: absolute;
      inset: -1px;
      background: linear-gradient(135deg, rgba(56, 189, 248, 0.35), rgba(129, 140, 248, 0.1), transparent 60%);
      opacity: 0.6;
      z-index: -1;
      mask: linear-gradient(#000, transparent);
    }

    /* ========================================
       COLOR PICKER INPUT SECTION
       ======================================== */
    .picker-section {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 32px;
      margin-bottom: 40px;
    }

    .picker-input-wrapper {
      display: flex;
      flex-direction: column;
      gap: 16px;
    }

    .picker-input-wrapper label {
      font-weight: 600;
      font-size: 1.05rem;
      color: var(--text-primary);
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .picker-input-wrapper label::before {
      content: "🎨";
      font-size: 1.2rem;
    }

    .color-input-group {
      display: flex;
      gap: 12px;
      align-items: center;
    }

    #colorPicker {
      width: 80px;
      height: 80px;
      border: 3px solid var(--border-color);
      border-radius: var(--radius-md);
      cursor: pointer;
      transition: var(--transition);
      background: transparent;
    }

    #colorPicker:hover {
      border-color: var(--accent-primary);
      transform: scale(1.05);
      box-shadow: 0 0 0 4px rgba(56, 189, 248, 0.2);
    }

    #colorPicker:focus {
      outline: none;
      border-color: var(--accent-primary);
      box-shadow: 0 0 0 4px rgba(56, 189, 248, 0.3);
    }

    .text-inputs {
      display: flex;
      flex-direction: column;
      gap: 10px;
      flex: 1;
    }

    .text-inputs input {
      width: 100%;
      padding: 12px 16px;
      background: rgba(15, 23, 42, 0.8);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-sm);
      color: var(--text-primary);
      font-size: 0.95rem;
      font-family: 'Courier New', monospace;
      transition: var(--transition);
    }

    .text-inputs input::placeholder {
      color: var(--text-muted);
    }

    .text-inputs input:focus {
      outline: none;
      border-color: var(--accent-primary);
      background: rgba(15, 23, 42, 0.95);
      box-shadow: 0 0 0 3px rgba(56, 189, 248, 0.2);
    }

    /* ========================================
       COLOR PREVIEW SECTION
       ======================================== */
    .preview-wrapper {
      display: flex;
      flex-direction: column;
      gap: 16px;
    }

    .preview-wrapper label {
      font-weight: 600;
      font-size: 1.05rem;
      color: var(--text-primary);
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .preview-wrapper label::before {
      content: "👁️";
      font-size: 1.2rem;
    }

    #colorPreview {
      width: 100%;
      height: 200px;
      border-radius: var(--radius-md);
      border: 3px solid var(--border-color);
      box-shadow: var(--shadow-md);
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 1.2rem;
      font-weight: 700;
      text-shadow: 0 2px 8px rgba(0, 0, 0, 0.5);
      transition: var(--transition);
      position: relative;
      overflow: hidden;
    }

    #colorPreview::before {
      content: "";
      position: absolute;
      inset: 0;
      background: 
        linear-gradient(45deg, rgba(0,0,0,0.1) 25%, transparent 25%),
        linear-gradient(-45deg, rgba(0,0,0,0.1) 25%, transparent 25%),
        linear-gradient(45deg, transparent 75%, rgba(0,0,0,0.1) 75%),
        linear-gradient(-45deg, transparent 75%, rgba(0,0,0,0.1) 75%);
      background-size: 20px 20px;
      background-position: 0 0, 0 10px, 10px -10px, -10px 0px;
      opacity: 0.3;
      z-index: -1;
    }

    /* ========================================
       COLOR CODES SECTION
       ======================================== */
    .color-codes {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
      gap: 16px;
      margin-bottom: 32px;
    }

    .code-item {
      background: rgba(15, 23, 42, 0.8);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-md);
      padding: 16px;
      display: flex;
      flex-direction: column;
      gap: 8px;
      transition: var(--transition);
    }

    .code-item:hover {
      border-color: var(--accent-primary);
      background: rgba(15, 23, 42, 0.95);
      transform: translateY(-2px);
      box-shadow: var(--shadow-md);
    }

    .code-label {
      font-size: 0.85rem;
      color: var(--text-secondary);
      font-weight: 600;
      text-transform: uppercase;
      letter-spacing: 0.5px;
    }

    .code-value {
      font-family: 'Courier New', monospace;
      font-size: 1.1rem;
      color: var(--text-primary);
      font-weight: 600;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 8px;
    }

    .copy-btn {
      background: linear-gradient(135deg, var(--accent-secondary), var(--accent-primary));
      border: none;
      border-radius: var(--radius-sm);
      padding: 6px 12px;
      color: #0b1120;
      font-weight: 600;
      font-size: 0.85rem;
      cursor: pointer;
      transition: var(--transition);
      display: flex;
      align-items: center;
      gap: 6px;
    }

    .copy-btn:hover {
      filter: brightness(1.1);
      transform: scale(1.05);
    }

    .copy-btn:active {
      transform: scale(0.98);
    }

    .copy-btn.copied {
      background: linear-gradient(135deg, var(--success), #16a34a);
    }

    /* ========================================
       CONTRAST CHECKER SECTION
       ======================================== */
    .contrast-section {
      background: linear-gradient(135deg, rgba(56, 189, 248, 0.08), rgba(129, 140, 248, 0.05));
      border: 1px solid rgba(56, 189, 248, 0.25);
      border-radius: var(--radius-md);
      padding: 24px;
      margin-bottom: 32px;
    }

    .contrast-section h3 {
      font-size: 1.2rem;
      margin-bottom: 16px;
      color: var(--text-primary);
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .contrast-section h3::before {
      content: "♿";
      font-size: 1.3rem;
    }

    .contrast-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
      gap: 16px;
    }

    .contrast-item {
      background: rgba(15, 23, 42, 0.6);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-sm);
      padding: 16px;
    }

    .contrast-preview {
      padding: 16px;
      border-radius: var(--radius-sm);
      margin-bottom: 12px;
      text-align: center;
      font-weight: 600;
      font-size: 1.05rem;
    }

    .contrast-ratio {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-bottom: 8px;
    }

    .ratio-value {
      font-family: 'Courier New', monospace;
      font-weight: 700;
      font-size: 1.1rem;
      color: var(--accent-primary);
    }

    .wcag-badges {
      display: flex;
      gap: 8px;
      flex-wrap: wrap;
    }

    .badge {
      padding: 4px 10px;
      border-radius: 999px;
      font-size: 0.75rem;
      font-weight: 600;
      text-transform: uppercase;
      letter-spacing: 0.5px;
    }

    .badge.pass {
      background: rgba(34, 197, 94, 0.2);
      color: var(--success);
      border: 1px solid var(--success);
    }

    .badge.fail {
      background: rgba(239, 68, 68, 0.2);
      color: var(--danger);
      border: 1px solid var(--danger);
    }

    /* ========================================
       COLOR SWATCHES SECTION
       ======================================== */
    .swatches-section {
      margin-bottom: 32px;
    }

    .swatches-section h3 {
      font-size: 1.2rem;
      margin-bottom: 16px;
      color: var(--text-primary);
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .swatches-section h3::before {
      content: "🎨";
      font-size: 1.3rem;
    }

    .swatches-grid {
      display: grid;
      grid-template-columns: repeat(auto-fill, minmax(80px, 1fr));
      gap: 12px;
    }

    .swatch {
      aspect-ratio: 1;
      border-radius: var(--radius-sm);
      border: 2px solid var(--border-color);
      cursor: pointer;
      transition: var(--transition);
      position: relative;
      overflow: hidden;
    }

    .swatch:hover {
      transform: scale(1.1);
      border-color: var(--accent-primary);
      box-shadow: 0 0 0 4px rgba(56, 189, 248, 0.2);
      z-index: 10;
    }

    .swatch::after {
      content: attr(data-color);
      position: absolute;
      bottom: 0;
      left: 0;
      right: 0;
      background: rgba(0, 0, 0, 0.8);
      color: white;
      font-size: 0.7rem;
      padding: 4px;
      text-align: center;
      opacity: 0;
      transition: var(--transition);
      font-family: 'Courier New', monospace;
    }

    .swatch:hover::after {
      opacity: 1;
    }

    /* ========================================
       FOOTER STYLES
       ======================================== */
    footer {
      max-width: var(--max-width);
      margin: 60px auto 32px;
      padding: 24px var(--container-padding);
      border-top: 1px solid var(--border-color);
      color: var(--text-secondary);
      font-size: 0.9rem;
      display: flex;
      justify-content: space-between;
      align-items: center;
      flex-wrap: wrap;
      gap: 16px;
    }

    footer a {
      color: #93c5fd;
      text-decoration: none;
      transition: var(--transition);
    }

    footer a:hover {
      color: var(--accent-primary);
      text-decoration: underline;
    }

    /* ========================================
       TOAST NOTIFICATION
       ======================================== */
    .toast {
      position: fixed;
      bottom: 32px;
      right: 32px;
      background: linear-gradient(135deg, var(--success), #16a34a);
      color: white;
      padding: 16px 24px;
      border-radius: var(--radius-md);
      box-shadow: var(--shadow-lg);
      display: flex;
      align-items: center;
      gap: 12px;
      font-weight: 600;
      opacity: 0;
      transform: translateY(20px);
      transition: var(--transition);
      pointer-events: none;
      z-index: 1000;
    }

    .toast.show {
      opacity: 1;
      transform: translateY(0);
      pointer-events: auto;
    }

    .toast::before {
      content: "✓";
      font-size: 1.5rem;
      font-weight: bold;
    }

    /* ========================================
       RESPONSIVE DESIGN
       ======================================== */
    @media (max-width: 768px) {
      .header-container {
        flex-direction: column;
        text-align: center;
      }

      .nav {
        flex-wrap: wrap;
        justify-content: center;
      }

      .logo img {
        height: 48px;
      }

      .page-title h2 {
        font-size: 2rem;
      }

      .picker-section {
        grid-template-columns: 1fr;
        gap: 24px;
      }

      .picker-card {
        padding: 24px;
      }

      .color-codes {
        grid-template-columns: 1fr;
      }

      .contrast-grid {
        grid-template-columns: 1fr;
      }

      .swatches-grid {
        grid-template-columns: repeat(auto-fill, minmax(60px, 1fr));
      }

      footer {
        flex-direction: column;
        text-align: center;
      }

      .toast {
        right: 16px;
        left: 16px;
        bottom: 16px;
      }
    }

    @media (max-width: 480px) {
      .page-title h2 {
        font-size: 1.6rem;
      }

      .color-input-group {
        flex-direction: column;
      }

      #colorPicker {
        width: 100%;
        height: 100px;
      }
    }

    /* ========================================
       ACCESSIBILITY IMPROVEMENTS
       ======================================== */
    .sr-only {
      position: absolute;
      width: 1px;
      height: 1px;
      padding: 0;
      margin: -1px;
      overflow: hidden;
      clip: rect(0, 0, 0, 0);
      white-space: nowrap;
      border-width: 0;
    }

    /* Focus visible for keyboard navigation */
    *:focus-visible {
      outline: 2px solid var(--accent-primary);
      outline-offset: 2px;
    }

    /* Reduced motion for accessibility */
    @media (prefers-reduced-motion: reduce) {
      *,
      *::before,
      *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
      }
    }