.theme-dark {
      --bg-canvas: #070E1A;
      --bg-surface: #0E1A2E;
      --bg-subtle: #16243C;
      --bg-muted: #1E3250;
      --text-main: #F1F5F9;
      --text-muted: #94A3B8;
      --text-faint: #64748B;
      --border-subtle: #1E2E48;
      --border-strong: #2D4468;
      
      /* Dark Trust Tiers */
      --tier-trusted-bg: #09281C;
      --tier-trusted-border: #34D399;
      --tier-trusted-text: #A7F3D0;
      
      --tier-medium-bg: #0F2548;
      --tier-medium-border: #60A5FA;
      --tier-medium-text: #BFDBFE;
      
      --tier-unverified-bg: #2B1D04;
      --tier-unverified-border: #F59E0B;
      --tier-unverified-text: #FDE68A;
      
      --tier-unknown-bg: #1B2433;
      --tier-unknown-border: #64748B;
      --tier-unknown-text: #CBD5E1;
      
      --focus-ring: #60A5FA;
      --brand-indigo: #3B82F6;
    }

    body {
      font-family: var(--font-sans);
      background-color: var(--bg-canvas);
      color: var(--text-main);
      -webkit-font-smoothing: antialiased;
    }

    .font-serif-clinical {
      font-family: var(--font-serif);
    }
    .font-mono-code {
      font-family: var(--font-mono);
    }

    /* Provenance Chip Base */
    .provenance-chip {
      display: inline-flex;
      align-items: center;
      gap: 5px;
      padding: 3px 8px 3px 6px;
      font-size: 11px;
      font-weight: 600;
      letter-spacing: 0.01em;
      border-radius: 9999px;
      line-height: 1.25;
      cursor: pointer;
      user-select: none;
      transition: all 0.15s cubic-bezier(0.4, 0, 0.2, 1);
      position: relative;
      outline: none;
    }

    .provenance-chip:focus-visible {
      outline: 2px solid var(--focus-ring);
      outline-offset: 2px;
    }

    /* 44x44px invisible tap target expansion for touch devices */
    .provenance-chip::before {
      content: '';
      position: absolute;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
      min-width: 44px;
      min-height: 44px;
      width: 100%;
      height: 100%;
    }

    /* Tier Variants */
    /* 1. Official Key (Pill, solid, double seal feel) */
    .chip-official {
      background-color: var(--tier-trusted-bg);
      border: 1px solid var(--tier-trusted-border);
      color: var(--tier-trusted-text);
      box-shadow: 0 1px 2px rgba(45, 159, 111, 0.08);
    }
    .chip-official:hover {
      background-color: #DDF3E8;
    }
    .theme-dark .chip-official:hover {
      background-color: #0E3626;
    }

    /* 2. Highlight PDF (Pill, solid, document icon) */
    .chip-pdf {
      background-color: var(--tier-trusted-bg);
      border: 1px solid var(--tier-trusted-border);
      color: var(--tier-trusted-text);
    }
    .chip-pdf:hover {
      background-color: #DDF3E8;
    }
    .theme-dark .chip-pdf:hover {
      background-color: #0E3626;
    }

    /* 3. Manual Entry (Pill, solid, pen icon) */
    .chip-manual {
      background-color: var(--tier-trusted-bg);
      border: 1px solid var(--tier-trusted-border);
      color: var(--tier-trusted-text);
    }
    .chip-manual:hover {
      background-color: #DDF3E8;
    }
    .theme-dark .chip-manual:hover {
      background-color: #0E3626;
    }

    /* 4. Vision Screenshot (Medium, square-rounded 6px, blue hue) */
    .chip-vision {
      background-color: var(--tier-medium-bg);
      border: 1px solid var(--tier-medium-border);
      color: var(--tier-medium-text);
      border-radius: 6px;
    }
    .chip-vision:hover {
      background-color: #DBEAFE;
    }
    .theme-dark .chip-vision:hover {
      background-color: #173461;
    }

    /* 5. Model Inferred (PROVISIONAL: Dashed 1.5px amber border, hazard stripes subtle pattern, amber tag) */
    .chip-model {
      background-color: var(--tier-unverified-bg);
      border: 1.5px dashed var(--tier-unverified-border);
      color: var(--tier-unverified-text);
      border-radius: 4px;
      font-weight: 700;
      position: relative;
    }
    .chip-model:hover {
      background-color: #FEF3C7;
    }
    .theme-dark .chip-model:hover {
      background-color: #382506;
    }

    /* 6. Unknown (Neutral gray, dotted border, calm) */
    .chip-unknown {
      background-color: var(--tier-unknown-bg);
      border: 1px dotted var(--tier-unknown-border);
      color: var(--tier-unknown-text);
      border-radius: 6px;
    }
    .chip-unknown:hover {
      background-color: #E7E2DA;
    }
    .theme-dark .chip-unknown:hover {
      background-color: #243044;
    }

    .clinical-val {
      white-space: nowrap;
      font-variant-numeric: tabular-nums;
    }

    /* Modal Backdrop */
    .modal-backdrop {
      background-color: rgba(15, 23, 42, 0.55);
      backdrop-filter: blur(3px);
    }