@layer base, layout, components, states, explore, responsive;

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

  :root {
    --bg:           #0f1117;
    --surface:      #1a1d27;
    --surface-2:    #242736;
    --border:       #2e3347;
    --text:         #e0e6f0;
    --text-dim:     #7a8099;
    --text-muted:   #4a5070;

    --green:        #7ed321;
    --blue:         #6ab0de;
    --orange:       #f5c563;

    --green-glow:   color-mix(in srgb, #7ed321 18%, transparent);
    --blue-glow:    color-mix(in srgb, #6ab0de 18%, transparent);
    --orange-glow:  color-mix(in srgb, #f5c563 18%, transparent);

    --green-dim:    color-mix(in srgb, #7ed321 12%, transparent);
    --blue-dim:     color-mix(in srgb, #6ab0de 12%, transparent);
    --orange-dim:   color-mix(in srgb, #f5c563 12%, transparent);

    --radius:    14px;
    --radius-sm: 8px;
    --radius-xs: 5px;
    --font: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
    --transition: 0.18s ease;
  }

  @media (prefers-color-scheme: light) {
    :root {
      --bg:        #f2f4f8;
      --surface:   #ffffff;
      --surface-2: #f0f2f7;
      --border:    #d4d8e8;
      --text:      #1a1d2e;
      --text-dim:  #5a6080;
      --text-muted:#9aa0bb;
    }
  }

  @media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
      animation-duration: 0.01ms !important;
      transition-duration: 0.01ms !important;
    }
  }

  html { font-size: 16px; scroll-behavior: smooth; }

  body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    min-height: 100dvh;
  }
}

@layer layout {
  .site-header {
    padding: 2rem 1.5rem 1.5rem;
    max-width: 680px;
    margin: 0 auto;
  }

  .site-header h1 {
    font-size: clamp(1.4rem, 4vw, 1.9rem);
    font-weight: 700;
    letter-spacing: -0.02em;
    color: var(--text);
    margin-bottom: 0.35rem;
  }

  .site-header p {
    font-size: 0.95rem;
    color: var(--text-dim);
  }

  main {
    max-width: 680px;
    margin: 0 auto;
    padding: 0 1.5rem 4rem;
  }

  footer {
    position: sticky;
    bottom: 0;
    z-index: 10;
    background: var(--bg);
    border-top: 1px solid var(--border);
  }

  .footer-inner {
    max-width: 680px;
    margin: 0 auto;
    padding: 0.75rem 1.5rem;
    display: flex;
    gap: 1.5rem;
    flex-wrap: wrap;
    align-items: center;
  }

  .legend {
    display: flex;
    gap: 1.25rem;
    flex-wrap: wrap;
    flex: 1;
  }

  .legend[hidden] { display: none; }

  .legend-item {
    display: flex;
    align-items: center;
    gap: 0.45rem;
    font-size: 0.8rem;
    color: var(--text-dim);
  }

  .legend-dot {
    width: 10px;
    height: 10px;
    border-radius: 3px;
    flex-shrink: 0;
  }

  .dot-oss      { background: var(--green); }
  .dot-closed   { background: var(--blue); }
  .dot-commercial { background: var(--orange); }

  .footer-credit {
    font-size: 0.78rem;
    color: var(--text-muted);
    margin-left: auto;
  }
}

@layer components {
  /* ── Breadcrumb ── */
  #breadcrumb {
    display: flex;
    flex-wrap: wrap;
    gap: 0.35rem;
    align-items: center;
    min-height: 2rem;
    margin-bottom: 1.25rem;
    font-size: 0.8rem;
  }

  .crumb {
    background: var(--surface-2);
    border: 1px solid var(--border);
    border-radius: var(--radius-xs);
    padding: 0.2rem 0.6rem;
    color: var(--text-dim);
    white-space: nowrap;
    max-width: 28ch;
    overflow: hidden;
    text-overflow: ellipsis;
  }

  .sep {
    color: var(--text-muted);
    user-select: none;
  }

  /* ── Card ── */
  .card {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 2rem;
    border: 1px solid var(--border);
    box-shadow: 0 2px 16px color-mix(in srgb, black 25%, transparent);
  }

  .card-eyebrow {
    font-size: 0.72rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--text-muted);
    margin-bottom: 0.75rem;
  }

  .card-eyebrow.cat-oss        { color: var(--green); }
  .card-eyebrow.cat-closed     { color: var(--blue); }
  .card-eyebrow.cat-commercial { color: var(--orange); }

  .card-title {
    font-size: clamp(1.2rem, 3.5vw, 1.55rem);
    font-weight: 700;
    letter-spacing: -0.01em;
    line-height: 1.25;
    margin-bottom: 0.5rem;
  }

  .card-sub {
    font-size: 0.92rem;
    color: var(--text-dim);
    margin-bottom: 1.75rem;
  }

  /* ── Options (question card) ── */
  .options {
    display: flex;
    flex-direction: column;
    gap: 0.65rem;
  }

  .option {
    display: block;
    width: 100%;
    padding: 0.9rem 1.2rem;
    background: var(--surface-2);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text);
    font-family: var(--font);
    font-size: 0.95rem;
    text-align: left;
    cursor: pointer;
    transition:
      border-color var(--transition),
      box-shadow var(--transition),
      transform var(--transition),
      background var(--transition);
  }

  .option:hover,
  .option:focus-visible {
    border-color: var(--blue);
    box-shadow: 0 0 0 3px var(--blue-glow), 0 2px 8px color-mix(in srgb, black 20%, transparent);
    transform: translateY(-1px);
    outline: none;
    background: color-mix(in srgb, var(--surface-2) 80%, var(--blue-dim));
  }

  .option:active {
    transform: translateY(0);
  }

  /* ── Result card ── */
  .result-head {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    margin-bottom: 1.25rem;
  }

  .result-icon {
    font-size: 2rem;
    line-height: 1;
    flex-shrink: 0;
    margin-top: 0.1rem;
  }

  .result-desc {
    font-size: 0.93rem;
    color: var(--text-dim);
    line-height: 1.65;
    margin-bottom: 1.25rem;
  }

  .features {
    list-style: none;
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(190px, 1fr));
    gap: 0.5rem;
    margin-bottom: 1.25rem;

    li {
      font-size: 0.85rem;
      color: var(--text-dim);
      background: var(--surface-2);
      border: 1px solid var(--border);
      border-radius: var(--radius-xs);
      padding: 0.35rem 0.7rem;
    }
  }

  .tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.75rem;
  }

  .tag {
    font-size: 0.75rem;
    font-weight: 500;
    border-radius: 999px;
    padding: 0.25rem 0.75rem;
    border: 1px solid;
  }

  .tag-oss        { color: var(--green);  border-color: var(--green-glow);  background: var(--green-dim); }
  .tag-closed     { color: var(--blue);   border-color: var(--blue-glow);   background: var(--blue-dim); }
  .tag-commercial { color: var(--orange); border-color: var(--orange-glow); background: var(--orange-dim); }

  .result-actions {
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
  }

  /* Card border accent by category */
  .card.result-oss        { border-color: color-mix(in srgb, var(--green) 35%, var(--border)); }
  .card.result-closed     { border-color: color-mix(in srgb, var(--blue) 35%, var(--border)); }
  .card.result-commercial { border-color: color-mix(in srgb, var(--orange) 35%, var(--border)); }

  /* ── Progress bar ── */
  #progress-bar {
    height: 3px;
    background: var(--border);
    margin-bottom: 1.5rem;
    border-radius: 999px;
    overflow: hidden;
  }

  #progress-fill {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, var(--blue), var(--green));
    border-radius: 999px;
    transition: width 0.4s ease;
  }

  /* ── Buttons ── */
  .btn-primary {
    display: inline-block;
    padding: 0.55rem 1.1rem;
    background: var(--blue);
    border: 1px solid var(--blue);
    border-radius: var(--radius-sm);
    color: var(--bg);
    font-family: var(--font);
    font-size: 0.87rem;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: opacity var(--transition), box-shadow var(--transition);
  }

  .btn-primary:hover,
  .btn-primary:focus-visible {
    opacity: 0.88;
    box-shadow: 0 0 0 3px var(--blue-glow);
    outline: none;
  }

  .btn-ghost {
    padding: 0.55rem 1.1rem;
    background: transparent;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text-dim);
    font-family: var(--font);
    font-size: 0.87rem;
    cursor: pointer;
    transition: border-color var(--transition), color var(--transition), background var(--transition);
  }

  .btn-ghost:hover,
  .btn-ghost:focus-visible {
    border-color: var(--blue);
    color: var(--blue);
    background: var(--blue-dim);
    outline: none;
  }

  /* ── Error state ── */
  .error {
    font-size: 0.9rem;
    color: #e07070;
    line-height: 1.7;

    code {
      background: var(--surface-2);
      padding: 0.1em 0.4em;
      border-radius: 4px;
      font-size: 0.85em;
    }
  }
}

@layer states {
  /* Card transition */
  .card {
    transition: opacity 0.13s ease, transform 0.13s ease;
  }

  .card.out {
    opacity: 0;
    transform: translateY(8px);
  }

  /* Explore tree highlights */
  .branch-label.chosen {
    background: var(--blue-dim);
    border-color: color-mix(in srgb, var(--blue) 50%, transparent) !important;
    color: var(--blue) !important;
  }

  .tree-leaf.visited {
    border-color: color-mix(in srgb, var(--green) 40%, transparent) !important;
    box-shadow: 0 0 10px var(--green-glow);
  }

  details[data-node].visited > summary {
    color: var(--blue);
  }
}

@layer explore {
  #explore {
    margin-top: 3rem;
  }

  #explore h2 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text);
  }

  #explore > p {
    font-size: 0.85rem;
    color: var(--text-dim);
    margin-bottom: 1.5rem;
  }

  .tree {
    font-size: 0.85rem;
  }

  .tree details {
    margin-left: 1.25rem;
    border-left: 2px solid var(--border);
    padding-left: 1rem;
    margin-bottom: 0.5rem;
  }

  .tree details > summary {
    cursor: pointer;
    font-weight: 500;
    color: var(--text-dim);
    padding: 0.3rem 0;
    list-style: none;
    transition: color var(--transition);
    user-select: none;
  }

  .tree details > summary:hover { color: var(--text); }
  .tree details > summary::before { content: '▸ '; font-size: 0.7em; }
  .tree details[open] > summary::before { content: '▾ '; }

  .branches { margin-top: 0.4rem; }

  .branch {
    margin-bottom: 0.5rem;
  }

  .branch-label {
    display: inline-block;
    font-size: 0.78rem;
    color: var(--text-muted);
    border: 1px solid var(--border);
    border-radius: var(--radius-xs);
    padding: 0.15rem 0.55rem;
    margin-bottom: 0.35rem;
    transition: background var(--transition), border-color var(--transition), color var(--transition);
  }

  .tree-leaf {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    font-size: 0.82rem;
    padding: 0.3rem 0.75rem;
    border-radius: var(--radius-xs);
    border: 1px solid var(--border);
    color: var(--text-dim);
    margin-top: 0.2rem;
    transition: border-color var(--transition), box-shadow var(--transition);
  }

  .tree-leaf.cat-oss        { color: var(--green); }
  .tree-leaf.cat-closed     { color: var(--blue); }
  .tree-leaf.cat-commercial { color: var(--orange); }
}

@layer responsive {
  @media (max-width: 480px) {
    .site-header { padding: 1.5rem 1rem 1rem; }
    main { padding: 0 1rem 3rem; }
    .card { padding: 1.5rem; }

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

    .result-actions {
      flex-direction: column;
    }

    .btn-ghost { width: 100%; text-align: center; }
  }
}