body, html {
      margin: 0;

      background-color: var(--bg-base);
      color: var(--text-main);
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
      -webkit-font-smoothing: antialiased;
    }

  /* Consolidated Mobile Navigation & Overlay Sidebar (<= 960px) */
  @media (max-width: 960px) {}

    /* Layout */
    .container {
      max-width: 1160px;
      margin: 0 auto;
      padding: 40px 20px 80px 20px;
    }

    .hero {
      text-align: center;
      margin-bottom: 36px;
    }

    .badge-pill {
      display: inline-flex;
      align-items: center;
      gap: 8px;
      padding: 6px 14px;
      background: rgba(0, 210, 255, 0.1);
      border: 1px solid rgba(0, 210, 255, 0.3);
      border-radius: 999px;
      color: var(--accent);
      font-size: 0.82rem;
      font-weight: 700;
      letter-spacing: 0.05em;
      text-transform: uppercase;
      margin-bottom: 16px;
    }

    h1 {
      font-size: 2.6rem;
      font-weight: 800;
      letter-spacing: -0.03em;
      margin: 0 0 12px 0;
      line-height: 1.2;
    }

    p.lead {
      color: var(--text-muted);
      font-size: 1.1rem;
      max-width: 720px;
      margin: 0 auto;
      line-height: 1.6;
    }

    /* Upload Box */
    .upload-box {
      background: var(--bg-card);
      border: 2px dashed rgba(0, 210, 255, 0.35);
      border-radius: 20px;
      padding: 50px 24px;
      text-align: center;
      cursor: pointer;
      transition: all 0.25s ease;
      margin-bottom: 32px;
    }

    .upload-box:hover, .upload-box.dragover {
      border-color: var(--accent);
      background: rgba(0, 210, 255, 0.04);
      transform: translateY(-2px);
    }

    .upload-icon {
      width: 56px;
      height: 56px;
      margin-bottom: 16px;
      color: var(--accent);
    }

    .upload-btn {
      display: inline-block;
      margin-top: 16px;
      padding: 10px 24px;
      background: var(--accent);
      color: #08090d;
      font-weight: 700;
      font-size: 0.95rem;
      border-radius: 10px;
      pointer-events: none;
    }

    /* Workspace */
    .workspace {
      display: none;
      background: var(--bg-card);
      border: 1px solid var(--border-color);
      border-radius: 20px;
      overflow: hidden;
      margin-bottom: 40px;
      box-shadow: 0 20px 40px rgba(0,0,0,0.4);
    }

    /* Control Toolbar */
    .toolbar {
      background: var(--bg-surface);
      border-bottom: 1px solid var(--border-color);
      padding: 14px 24px;
      display: flex;
      flex-wrap: wrap;
      align-items: center;
      justify-content: space-between;
      gap: 16px;
    }

    .toolbar-group {
      display: flex;
      align-items: center;
      gap: 10px;
    }

    .tool-btn {
      background: var(--bg-surface);
      border: 1px solid var(--border-color);
      color: var(--text-main);
      padding: 8px 14px;
      border-radius: 8px;
      font-size: 0.88rem;
      font-weight: 600;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      transition: all 0.2s;
    }

    .tool-btn:hover {
      background: var(--bg-surface);
      border-color: var(--accent);
      color: var(--accent);
    }

    .tool-btn.active {
      background: rgba(0, 210, 255, 0.15);
      border-color: var(--accent);
      color: var(--accent);
    }

    .tool-btn:disabled {
      opacity: 0.4;
      cursor: not-allowed;
      border-color: transparent;
    }

    .page-indicator {
      font-size: 0.92rem;
      font-weight: 700;
      color: var(--text-main);
      padding: 0 8px;
    }

    .zoom-indicator {
      font-size: 0.86rem;
      font-weight: 700;
      color: var(--accent);
      background: rgba(0, 210, 255, 0.1);
      border: 1px solid rgba(0, 210, 255, 0.25);
      border-radius: 6px;
      padding: 6px 10px;
      cursor: pointer;
      user-select: none;
      transition: all 0.2s;
    }
    .zoom-indicator:hover {
      background: rgba(0, 210, 255, 0.25);
      border-color: var(--accent);
    }

        .document-group {
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .current-filename {
      font-size: 0.82rem;
      font-weight: 500;
      color: var(--text-muted);
      max-width: 170px;
      white-space: nowrap;
      overflow: hidden;
      text-overflow: ellipsis;
      background: rgba(255, 255, 255, 0.04);
      border: 1px solid rgba(255, 255, 255, 0.08);
      padding: 6px 12px;
      border-radius: 6px;
      display: inline-block;
      vertical-align: middle;
    }

    .tool-btn-secondary {
      background: rgba(255, 255, 255, 0.03);
      border-color: rgba(255, 255, 255, 0.12);
      color: var(--text-muted);
    }
    .tool-btn-secondary:hover {
      background: rgba(239, 68, 68, 0.12);
      border-color: rgba(239, 68, 68, 0.4);
      color: #f87171;
    }

    .export-btn {
      background: var(--accent);
      color: #08090d;
      border: none;
      padding: 10px 22px;
      border-radius: 8px;
      font-weight: 800;
      font-size: 0.95rem;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 8px;
      transition: all 0.2s;
    }

    .export-btn:hover {
      background: #4ae0ff;
      box-shadow: 0 0 20px rgba(0, 210, 255, 0.4);
    }

    /* Metadata Inspection Box */
    .metadata-panel {
      padding: 14px 24px;
      background: rgba(0, 0, 0, 0.25);
      border-bottom: 1px solid var(--border-color);
      display: flex;
      flex-wrap: wrap;
      align-items: center;
      justify-content: space-between;
      gap: 16px;
      font-size: 0.88rem;
    }

    .meta-summary {
      color: var(--text-muted);
      display: flex;
      align-items: center;
      gap: 16px;
      flex-wrap: wrap;
    }

    .meta-badge {
      padding: 4px 10px;
      border-radius: 6px;
      font-weight: 700;
      font-size: 0.78rem;
    }

    .meta-badge.detected {
      background: rgba(239, 68, 68, 0.15);
      border: 1px solid rgba(239, 68, 68, 0.4);
      color: #f87171;
    }

    .meta-badge.clean {
      background: rgba(34, 197, 94, 0.15);
      border: 1px solid rgba(34, 197, 94, 0.4);
      color: #4ade80;
    }

    .meta-toggle {
      display: flex;
      align-items: center;
      gap: 8px;
      cursor: pointer;
      color: var(--text-main);
      font-weight: 600;
    }

    /* Canvas Stage with Touch-Friendly High-Contrast Scrollbars */
    .stage-container {
      background: var(--bg-base);
      padding: 24px 24px 100px 24px;
      min-height: 480px;
      max-height: 75vh;
      overflow: auto;
      -webkit-overflow-scrolling: touch;
      position: relative;
      scrollbar-color: var(--accent) #11141d;
      scrollbar-width: auto;
      box-sizing: border-box;
    }

    /* Stage Outer Wrapper: Pins floating HUD stably over the stage without scrolling */
    .stage-wrapper {
      position: relative;
      width: 100%;
    }

    /* Floating History HUD pinned permanently in top-right of editing stage */
    .stage-floating-hud {
      position: absolute;
      top: 14px;
      right: 18px;
      z-index: 150;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      background: color-mix(in srgb, var(--bg-surface) 88%, transparent);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      border: 1px solid rgba(0, 210, 255, 0.35);
      border-radius: 999px;
      padding: 4px 8px;
      box-shadow: 0 8px 24px rgba(0, 0, 0, 0.6);
      pointer-events: auto;
      transition: all 0.2s ease;
      user-select: none;
    }

    .stage-floating-hud:hover {
      background: color-mix(in srgb, var(--bg-surface) 88%, transparent);
      border-color: var(--accent);
      box-shadow: 0 8px 28px rgba(0, 0, 0, 0.7), 0 0 15px rgba(0, 210, 255, 0.25);
    }

    .hud-btn {
      background: var(--bg-surface);
      border: 1px solid var(--border-color);
      color: var(--text-main);
      padding: 6px 14px;
      border-radius: 999px;
      font-size: 0.82rem;
      font-weight: 700;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 5px;
      transition: all 0.2s;
    }

    .hud-btn:hover:not(:disabled) {
      background: var(--bg-surface);
      border-color: var(--accent);
      color: var(--accent);
      transform: translateY(-1px);
    }

    .hud-btn:active:not(:disabled) {
      transform: scale(0.96);
    }

    .hud-btn:disabled {
      opacity: 0.35;
      cursor: not-allowed;
      border-color: transparent;
    }

    /* Inner stage ensures centered layout when small, but expands positively when zoomed in with ZERO clipping */
    .stage-inner {
      display: inline-flex;
      min-width: 100%;
      min-height: 100%;
      justify-content: center;
      align-items: flex-start;
      padding-bottom: 40px;
      box-sizing: border-box;
    }

    /* Desktop Scrollbars: 18px Comfortable Target */
    .stage-container::-webkit-scrollbar {
      width: 18px;
      height: 18px;
    }
    .stage-container::-webkit-scrollbar-track {
      background: var(--bg-card);
      border-radius: 8px;
      border: 2px solid #0b0d13;
    }
    .stage-container::-webkit-scrollbar-thumb {
      background: var(--bg-surface);
      border: 3px solid #11141d;
      border-radius: 10px;
      min-height: 48px;
      min-width: 48px;
    }
    .stage-container::-webkit-scrollbar-thumb:hover,
    .stage-container::-webkit-scrollbar-thumb:active {
      background: var(--accent);
      box-shadow: 0 0 12px rgba(0, 210, 255, 0.5);
    }

    /* Floating Navigation Dock Wrapper (Guarantees Pixel-Perfect Centering on Mobile) */
    .dock-wrapper {
      display: flex;
      justify-content: center;
      align-items: center;
      width: 100%;
      margin-top: -68px;
      margin-bottom: 24px;
      position: relative;
      z-index: 120;
      pointer-events: none;
      padding: 0 10px;
      box-sizing: border-box;
    }

    .quick-nav-dock {
      pointer-events: auto;
      background: color-mix(in srgb, var(--bg-surface) 88%, transparent);
      backdrop-filter: blur(14px);
      border: 1px solid rgba(0, 210, 255, 0.4);
      border-radius: 999px;
      padding: 6px 12px;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      box-shadow: 0 10px 30px rgba(0, 0, 0, 0.7), 0 0 20px rgba(0, 210, 255, 0.2);
      max-width: 100%;
      flex-wrap: nowrap;
    }

    .dock-mode-toggle {
      background: rgba(0, 210, 255, 0.15);
      border: 1px solid #00d2ff;
      color: var(--accent);
      font-size: 0.85rem;
      font-weight: 700;
      padding: 7px 14px;
      border-radius: 999px;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      white-space: nowrap;
      transition: all 0.2s;
    }
    .dock-mode-toggle.pan-active {
      background: var(--accent);
      color: #08090d;
      box-shadow: 0 0 14px rgba(0, 210, 255, 0.5);
    }

    .dock-divider {
      width: 1px;
      height: 20px;
      background: var(--bg-surface);
    }

    .dock-nudge-btn {
      background: var(--bg-surface);
      border: 1px solid var(--border-color);
      color: var(--text-main);
      width: 36px;
      height: 36px;
      border-radius: 50%;
      font-size: 0.85rem;
      font-weight: 700;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      transition: all 0.2s;
    }
    .dock-nudge-btn:hover, .dock-nudge-btn:active {
      background: var(--bg-surface);
      border-color: var(--accent);
      color: var(--accent);
      transform: scale(1.1);
    }

    .canvas-wrapper {
      position: relative;
      box-shadow: 0 10px 30px rgba(0, 0, 0, 0.7);
      background: #ffffff;
      border-radius: 4px;
      line-height: 0;
      user-select: none;
      flex-shrink: 0;
      transform-origin: center center;
      will-change: transform;
    }

    #pdf-canvas {
      display: block;
    }

    .page-select {
      background: var(--bg-surface);
      border: 1px solid var(--border-color);
      color: var(--text-main);
      padding: 6px 10px;
      border-radius: 6px;
      font-size: 0.88rem;
      font-weight: 600;
      cursor: pointer;
      outline: none;
    }
    .page-select:focus {
      border-color: var(--accent);
    }

    #draw-canvas {
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      cursor: crosshair;
      touch-action: none;
      -webkit-touch-callout: none;
      user-select: none;
      -webkit-user-select: none;
    }

    /* Mobile Responsive Controls */
    @media (max-width: 640px) {
      .toolbar {
        padding: 12px 14px;
        gap: 10px;
      }
      .toolbar-group {
        width: 100%;
        justify-content: space-between;
        flex-wrap: wrap;
        gap: 8px;
      }
      .export-btn {
        flex: 1 1 auto;
        justify-content: center;
        padding: 10px 12px;
        font-size: 0.84rem;
        min-height: 42px;
      }
      .stage-container {
        padding: 20px 20px 140px 20px;
        min-height: 380px;
        max-height: 70vh;
      }
      /* Extra-Thick 26px Touch Scrollbars on Mobile */
      .stage-container::-webkit-scrollbar {
        width: 26px;
        height: 26px;
      }
      .stage-container::-webkit-scrollbar-track {
        background: var(--bg-card);
        border: 2px solid #08090d;
        border-radius: 12px;
      }
      .stage-container::-webkit-scrollbar-thumb {
        background: var(--accent);
        border: 4px solid #151926;
        border-radius: 16px;
        min-height: 56px;
        min-width: 56px;
        box-shadow: 0 0 10px rgba(0, 210, 255, 0.4);
      }
      .hint-bar {
        font-size: 0.8rem;
        padding: 10px 14px;
        flex-direction: column;
        align-items: flex-start;
        gap: 6px;
      }
      .metadata-panel {
        padding: 12px 14px;
      }}

    /* Instruction banner */
    .hint-bar {
      padding: 10px 24px;
      background: rgba(0, 210, 255, 0.06);
      border-bottom: 1px solid rgba(0, 210, 255, 0.15);
      color: var(--text-muted);
      font-size: 0.86rem;
      display: flex;
      align-items: center;
      justify-content: space-between;
    }

    .hint-bar span strong { color: var(--accent); }

    /* Progress overlay */
    .progress-overlay {
      position: fixed;
      inset: 0;
      background: rgba(8, 9, 13, 0.85);
      backdrop-filter: blur(8px);
      display: none;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      z-index: 2000;
    }

    .spinner {
      width: 48px;
      height: 48px;
      border: 4px solid rgba(0, 210, 255, 0.2);
      border-top-color: var(--accent);
      border-radius: 50%;
      animation: spin 0.8s linear infinite;
      margin-bottom: 20px;
    }

    @keyframes spin { to { transform: rotate(360deg); }}

    /* Content & FAQs */
    .info-section {
      margin-top: 60px;
      border-top: 1px solid var(--border-color);
      padding-top: 50px;
    }

    .features-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
      gap: 24px;
      margin-bottom: 60px;
    }

    .feature-card {
      background: var(--bg-card);
      border: 1px solid var(--border-color);
      border-radius: 16px;
      padding: 28px;
    }

    .feature-icon {
      margin-bottom: 16px;
      color: var(--accent);
      display: inline-flex;
    }

    .feature-card h3 {
      font-size: 1.25rem;
      margin: 0 0 12px 0;
      color: var(--text-main);
      display: flex;
      align-items: center;
      gap: 10px;
    }

    .feature-card h3 span { color: var(--accent); }
    .feature-card p {
      color: var(--text-muted);
      font-size: 0.92rem;
      line-height: 1.6;
      margin: 0;
    }

    .faq-title {
      font-size: 1.8rem;
      font-weight: 800;
      letter-spacing: -0.02em;
      text-align: left;
      margin-bottom: 24px;
    }

    .faq-box {
      background: var(--bg-card);
      border: 1px solid var(--border-color);
      border-radius: 12px;
      margin-bottom: 16px;
      overflow: hidden;
    }

    .faq-box summary {
      padding: 18px 24px;
      font-weight: 700;
      cursor: pointer;
      font-size: 1.05rem;
      color: var(--text-main);
      outline: none;
      list-style: none;
    }
    .faq-box summary::-webkit-details-marker { display: none; }

    .faq-box p {
      padding: 0 24px 20px 24px;
      margin: 0;
      color: var(--text-muted);
      line-height: 1.6;
      font-size: 0.95rem;
    }

    @media (prefers-reduced-motion: reduce) {
      *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
      }}