/* Dark Theme Mimicking Desktop GUI */
    :root {
      --bg-dark: #0a111a;
      --bg-panel: #111a24;
      --bg-input: #0f1722;
      --border-color: #1e2b3c;
      --text-main: #cbd5e1;
      --text-muted: #64748b;
      --accent-blue: #0ea5e9;
      --accent-hover: #0284c7;
      --font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    }
    
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      background-color: var(--bg-dark);
      color: var(--text-main);
      font-family: var(--font-family);
      font-size: 13px;
      height: 100vh;
      display: flex;
      flex-direction: column;
    }

    /* Top Navigation Bar */
    header {
      background-color: #050a10;
      padding: 8px 16px;
      font-size: 12px;
      color: #fff;
      display: flex;
      align-items: center;
    }
    header .icon { margin-right: 8px; color: var(--accent-blue); }

    /* Drag & Drop Area */
    .drop-zone {
      margin: 16px;
      border: 1px dashed var(--border-color);
      border-radius: 4px;
      padding: 24px;
      text-align: center;
      color: var(--text-muted);
      cursor: pointer;
      background-color: var(--bg-panel);
    }
    .drop-zone:hover { border-color: var(--accent-blue); }

    /* Main Grid */
    .main-grid {
      display: flex;
      flex: 1;
      overflow: hidden;
      padding: 0 16px;
      gap: 16px;
    }

    /* Left Column (Settings) */
    .left-col {
      width: 45%;
      min-width: 400px;
      overflow-y: auto;
      padding-right: 12px;
    }

    /* Right Column (Preview) */
    .right-col {
      flex: 1;
      display: flex;
      flex-direction: column;
    }

    /* Section Styles */
    .section-title {
      font-size: 10px;
      text-transform: uppercase;
      color: var(--text-muted);
      margin-bottom: 8px;
      margin-top: 16px;
      letter-spacing: 0.5px;
    }
    .section-title:first-child { margin-top: 0; }

    /* Inputs & Controls */
    select, input[type="text"], input[type="number"] {
      width: 100%;
      background-color: var(--bg-input);
      border: 1px solid var(--border-color);
      color: var(--text-main);
      padding: 6px 8px;
      border-radius: 4px;
      outline: none;
    }
    select:focus, input:focus { border-color: var(--accent-blue); }
    
    .row {
      display: flex;
      gap: 8px;
      align-items: center;
      margin-bottom: 8px;
    }
    .space-between {
      justify-content: space-between;
    }
    
    .btn {
      background-color: transparent;
      border: 1px solid var(--border-color);
      color: var(--text-main);
      padding: 4px 10px;
      border-radius: 4px;
      cursor: pointer;
      transition: all 0.2s;
      font-size: 12px;
    }
    .btn:hover { background-color: var(--bg-input); }
    .btn.active {
      border-color: var(--accent-blue);
      color: var(--accent-blue);
    }

    .btn-group {
      display: flex;
      gap: 4px;
      flex-wrap: wrap;
    }

    /* Counter Control for Copies */
    .counter-ctrl {
      display: flex;
      align-items: center;
      border: 1px solid var(--border-color);
      border-radius: 4px;
      overflow: hidden;
      width: 100px;
    }
    .counter-ctrl button {
      background: var(--bg-input);
      border: none;
      color: var(--text-main);
      padding: 4px 10px;
      cursor: pointer;
    }
    .counter-ctrl button:hover { background: var(--border-color); }
    .counter-ctrl input {
      border: none;
      border-left: 1px solid var(--border-color);
      border-right: 1px solid var(--border-color);
      text-align: center;
      padding: 4px 0;
      border-radius: 0;
    }

    .btn-primary {
      background-color: var(--accent-blue);
      color: white;
      border: none;
      padding: 8px 24px;
      font-weight: 600;
    }
    .btn-primary:hover { background-color: var(--accent-hover); }

    /* Checkboxes */
    .checkbox-row {
      display: flex;
      align-items: center;
      margin-bottom: 8px;
      cursor: pointer;
      color: var(--text-main);
    }
    .checkbox-row input { margin-right: 8px; accent-color: var(--accent-blue); }

    /* Preview Box */
    .preview-box {
      flex: 1;
      background-color: var(--bg-panel);
      border: 1px solid var(--border-color);
      border-radius: 4px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--text-muted);
      margin-top: 8px;
    }

    /* Footer */
    footer {
      padding: 16px;
      display: flex;
      justify-content: flex-end;
      align-items: center;
      gap: 12px;
      border-top: 1px solid var(--border-color);
      margin-top: 16px;
    }

    /* Utilities */
    .flex-1 { flex: 1; }
    
    /* Range slider styling */
    input[type=range] {
      -webkit-appearance: none;
      width: 100%;
      background: transparent;
      margin: 8px 0;
    }
    input[type=range]::-webkit-slider-thumb {
      -webkit-appearance: none;
      height: 12px;
      width: 12px;
      border-radius: 50%;
      background: var(--text-main);
      cursor: pointer;
      margin-top: -4px;
    }
    input[type=range]::-webkit-slider-runnable-track {
      width: 100%;
      height: 4px;
      cursor: pointer;
      background: var(--border-color);
      border-radius: 2px;
    }
    
    .margin-value {
      background-color: var(--bg-input);
      border: 1px solid var(--border-color);
      padding: 2px 8px;
      font-size: 11px;
    }
    
    #fileInput { display: none; }
  </style>