.file-drop-area {
            border: 3px dashed var(--border-color);
            border-radius: 12px;
            padding: 2.5rem 2rem;
            text-align: center;
            background-color: #fafbfc;
            transition: all 0.3s ease;
            cursor: pointer;
            margin: 1rem 0;
        }
        .file-drop-area:hover,
        .file-drop-area.dragover {
            border-color: var(--primary-color);
            background-color: rgba(70, 130, 180, 0.04);
        }
        .file-drop-area .file-icon {
            font-size: 3.5rem;
            color: var(--primary-color);
            margin-bottom: 0.75rem;
        }
        .file-drop-area .file-label {
            font-weight: 500;
            font-size: 1.1rem;
        }
        .file-drop-area .file-hint {
            color: var(--text-muted);
            font-size: 0.9rem;
        }
        .file-info {
            background-color: #f0f4f9;
            border-radius: 8px;
            padding: 1rem 1.5rem;
            display: none;
            align-items: center;
            gap: 1rem;
            margin: 1rem 0;
            flex-wrap: wrap;
        }
        .file-info .file-detail {
            flex: 1;
            min-width: 150px;
        }
        .file-info .file-name {
            font-weight: 600;
            word-break: break-all;
        }
        .file-info .file-meta {
            font-size: 0.9rem;
            color: var(--text-muted);
        }
        .file-info .file-remove {
            color: #dc3545;
            cursor: pointer;
            font-size: 1.2rem;
            padding: 0 0.5rem;
            transition: transform 0.2s;
        }
        .file-info .file-remove:hover {
            transform: scale(1.2);
        }
        .password-section {
            background-color: #fff3cd;
            border: 1px solid #ffc107;
            border-radius: 8px;
            padding: 0.75rem 1.25rem;
            margin: 0.5rem 0 1rem;
            display: none;
            align-items: center;
            gap: 0.75rem;
            flex-wrap: wrap;
        }
        .password-section label {
            font-weight: 500;
            margin: 0;
        }
        .password-section input {
            flex: 1;
            min-width: 150px;
            max-width: 300px;
        }
        .split-options {
            background-color: #f8f9fa;
            border-radius: 8px;
            padding: 1.5rem;
            margin: 1.5rem 0;
        }
        .split-options .form-label {
            font-weight: 500;
        }
        .split-options .radio-group {
            display: flex;
            flex-wrap: wrap;
            gap: 1.5rem;
            margin: 0.5rem 0 1rem;
        }
        .split-options .radio-group .form-check {
            margin-right: 0.5rem;
        }
        .range-input-group {
            display: none;
            margin-top: 0.75rem;
        }
        .range-input-group .input-group-text {
            background-color: #e9ecef;
            font-weight: 500;
        }
        .page-preview {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(90px, 1fr));
            gap: 0.75rem;
            margin: 1rem 0;
            max-height: 320px;
            overflow-y: auto;
            padding: 0.5rem;
            border: 1px solid #e9ecef;
            border-radius: 6px;
            background: #fff;
        }
        .page-preview .page-thumb {
            background: #f1f3f5;
            border-radius: 4px;
            padding: 0.5rem;
            text-align: center;
            font-size: 0.8rem;
            border: 2px solid transparent;
            transition: border 0.2s;
            cursor: default;
        }
        .page-preview .page-thumb.selected {
            border-color: var(--primary-color);
            background: #e7f0fa;
        }
        .page-preview .page-thumb .page-number {
            font-weight: 600;
            color: var(--accent-color);
        }
        .page-preview .page-thumb .page-icon {
            font-size: 1.8rem;
            color: #6c757d;
            display: block;
            margin: 0.2rem auto;
        }
        .split-result-item {
            background: #fff;
            border: 1px solid #e9ecef;
            border-radius: 8px;
            padding: 1rem 1.25rem;
            margin-bottom: 0.75rem;
            display: flex;
            justify-content: space-between;
            align-items: center;
            flex-wrap: wrap;
            transition: box-shadow 0.2s;
        }
        .split-result-item:hover {
            box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
        }
        .split-result-item .part-info {
            display: flex;
            align-items: center;
            gap: 0.75rem;
            flex-wrap: wrap;
        }
        .split-result-item .part-badge {
            background: var(--primary-color);
            color: #fff;
            border-radius: 20px;
            padding: 0.2rem 0.8rem;
            font-size: 0.8rem;
            font-weight: 600;
        }
        .split-result-item .part-pages {
            color: var(--text-muted);
            font-size: 0.9rem;
        }
        .split-result-item .part-actions {
            display: flex;
            gap: 0.5rem;
        }
        .split-result-item .part-actions .btn-sm {
            font-size: 0.8rem;
        }
        .split-summary {
            background: #e7f3ff;
            border-radius: 8px;
            padding: 1rem 1.5rem;
            margin: 1rem 0;
            border-left: 4px solid var(--primary-color);
        }
        .split-summary .summary-number {
            font-weight: 700;
            font-size: 1.3rem;
            color: var(--primary-color);
        }
        .property-table th,
        .property-table td {
            padding: 0.75rem;
            text-align: left;
            border: 1px solid var(--border-color);
        }
        .property-table th {
            background-color: var(--light-gray);
            font-weight: 600;
        }
        .property-table tr:nth-child(even) {
            background-color: rgba(70, 130, 180, 0.04);
        }
        .authority-note {
            font-size: 0.85rem;
            color: var(--text-muted);
            border-top: 1px solid var(--border-color);
            padding-top: 1rem;
            margin-top: 1rem;
            text-align: right;
        }
        .case-study {
            background-color: #f0f7fa;
            border-radius: 8px;
            padding: 1.5rem;
            margin: 1.5rem 0;
            border-left: 5px solid var(--primary-color);
        }
        .key-point {
            font-weight: 500;
            color: var(--accent-color);
        }
        .math-equation {
            font-size: 1.1rem;
            padding: 15px;
            background-color: rgba(70, 130, 180, 0.05);
            border-left: 4px solid var(--primary-color);
            border-radius: 4px;
            margin: 15px 0;
        }
        .privacy-note {
            font-size: 0.9rem;
            background-color: #e7f3ff;
            border: 1px solid #b8daff;
            color: #004085;
            padding: 0.5rem 1rem;
            border-radius: 4px;
            margin: 1rem 0;
        }
        .warning-note {
            background-color: #fff3cd;
            border: 1px solid #ffeeba;
            color: #856404;
            padding: 0.5rem 1rem;
            border-radius: 4px;
            margin: 1rem 0;
            display: none;
        }
        .author-bio {
            background-color: #f8f9fa;
            border-left: 4px solid var(--primary-color);
            padding: 1.2rem;
            margin: 2rem 0;
            border-radius: 0 8px 8px 0;
        }
        .deep-dive p {
            text-align: justify;
        }
        .function-examples {
            display: flex;
            flex-wrap: wrap;
            gap: 0.5rem;
            margin: 0.5rem 0 1rem;
        }
        .example-btn {
            background-color: rgba(70, 130, 180, 0.08);
            border: 1px solid rgba(70, 130, 180, 0.2);
            border-radius: 4px;
            padding: 0.4rem 0.8rem;
            font-size: 0.85rem;
            color: var(--primary-color);
            cursor: pointer;
            transition: all 0.2s;
        }
        .example-btn:hover {
            background-color: rgba(70, 130, 180, 0.18);
            transform: translateY(-2px);
        }
        .subsection-title {
            font-weight: 600;
            margin-top: 2rem;
            margin-bottom: 1rem;
            color: var(--accent-color);
            font-size: 1.2rem;
        }
        .math-box {
            background-color: rgba(70, 130, 180, 0.05);
            border-left: 3px solid var(--primary-color);
            padding: 1rem;
            border-radius: 0 4px 4px 0;
            margin: 1.5rem 0;
        }
        .result-row {
            font-size: 1.1rem;
            margin: 0.4rem 0;
        }
        .result-value {
            font-weight: 600;
            color: var(--primary-color);
        }
        .result-title {
            font-weight: 700;
            font-size: 1.4rem;
            margin-bottom: 1rem;
            color: var(--accent-color);
        }
        .toast-container {
            position: fixed;
            bottom: 20px;
            right: 20px;
            z-index: 1050;
        }
        .progress-wrapper {
            height: 6px;
            background: #e9ecef;
            border-radius: 4px;
            margin: 0.75rem 0;
            overflow: hidden;
            display: none;
        }
        .progress-wrapper .progress-bar {
            height: 100%;
            background: var(--primary-color);
            width: 0%;
            border-radius: 4px;
            transition: width 0.3s ease;
        }
        @media (max-width: 576px) {
            .split-options .radio-group {
                flex-direction: column;
                gap: 0.5rem;
            }
            .page-preview {
                grid-template-columns: repeat(auto-fill, minmax(70px, 1fr));
            }
            .split-result-item {
                flex-direction: column;
                align-items: stretch;
                gap: 0.5rem;
            }
            .split-result-item .part-actions {
                justify-content: flex-start;
            }
            .file-info {
                flex-direction: column;
                align-items: stretch;
                text-align: center;
            }
        }