:root {
            --primary: #4f46e5;
            --primary-hover: #4338ca;
            --secondary: #06b6d4;
            --bg: #f8fafc;
            --card: #ffffff;
            --text: #1e293b;
            --text-secondary: #64748b;
            --border: #e2e8f0;
            --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
            --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
            --radius: 12px;
        }
        
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        
        body {
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
            background: var(--bg);
            color: var(--text);
            line-height: 1.6;
            min-height: 100vh;
        }
        
        .container {
            max-width: 960px;
            margin: 0 auto;
            padding: 0 16px;
        }
        
        /* Header */
        .page-header {
            text-align: center;
            padding: 48px 16px 32px;
            background: linear-gradient(135deg, #4f46e5 0%, #06b6d4 100%);
            color: white;
            margin-bottom: 32px;
        }
        
        .page-header h1 {
            font-size: 2rem;
            font-weight: 700;
            margin-bottom: 8px;
            letter-spacing: -0.02em;
        }
        
        .page-header p {
            font-size: 1rem;
            opacity: 0.9;
            max-width: 600px;
            margin: 0 auto;
        }
        
        /* Tool Section */
        .tool-section {
            background: var(--card);
            border-radius: var(--radius);
            box-shadow: var(--shadow-lg);
            padding: 28px;
            margin-bottom: 40px;
        }
    
        
        .converter-box {
            display: flex;
            flex-direction: column;
            gap: 16px;
        }
        
        .textarea-wrapper {
            position: relative;
        }
        
        .textarea-wrapper label {
            display: block;
            font-size: 0.875rem;
            font-weight: 500;
            color: var(--text-secondary);
            margin-bottom: 6px;
        }
        
        textarea {
            width: 100%;
            min-height: 120px;
            padding: 14px 16px;
            border: 1px solid var(--border);
            border-radius: 10px;
            font-size: 1rem;
            font-family: inherit;
            resize: vertical;
            transition: all 0.2s;
            background: var(--bg);
        }
        
        textarea:focus {
            outline: none;
            border-color: var(--primary);
            box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
            background: var(--card);
        }
        
        .char-count {
            text-align: right;
            font-size: 0.75rem;
            color: var(--text-secondary);
            margin-top: 4px;
        }
        
        /* Mode Selector */
        .mode-selector {
            display: flex;
            flex-wrap: wrap;
            gap: 10px;
            margin-bottom: 4px;
        }
        
        .mode-btn {
            padding: 8px 18px;
            border: 1px solid var(--border);
            background: var(--card);
            border-radius: 20px;
            font-size: 0.875rem;
            font-weight: 500;
            color: var(--text-secondary);
            cursor: pointer;
            transition: all 0.2s;
            user-select: none;
        }
        
        .mode-btn:hover {
            border-color: var(--primary);
            color: var(--primary);
        }
        
        .mode-btn.active {
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            color: white;
            border-color: transparent;
            box-shadow: 0 4px 6px -1px rgba(79, 70, 229, 0.3);
        }
        
        .mode-desc {
            font-size: 0.8rem;
            color: var(--text-secondary);
            margin-top: 4px;
            min-height: 1.2em;
        }
        
        /* Action Buttons */
        .action-bar {
            display: flex;
            flex-wrap: wrap;
            gap: 12px;
            align-items: center;
        }
        
        .btn {
            padding: 10px 24px;
            border: none;
            border-radius: 8px;
            font-size: 0.9375rem;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.2s;
            display: inline-flex;
            align-items: center;
            gap: 6px;
        }
        
        .btn-primary {
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            color: white;
            box-shadow: 0 4px 6px -1px rgba(79, 70, 229, 0.3);
        }
        
        .btn-primary:hover {
            transform: translateY(-1px);
            box-shadow: 0 6px 12px -2px rgba(79, 70, 229, 0.4);
        }
        
        .btn-primary:active {
            transform: translateY(0);
        }
        
        .btn-secondary {
            background: var(--bg);
            color: var(--text);
            border: 1px solid var(--border);
        }
        
        .btn-secondary:hover {
            background: var(--border);
        }
        
        .btn-success {
            background: #10b981;
            color: white;
        }
        
        .btn-success:hover {
            background: #059669;
        }
        
        /* Output Area */
        .output-area {
            position: relative;
        }
        
        .output-area textarea {
            background: linear-gradient(to bottom right, #fafafa, #f0f9ff);
            font-size: 1.125rem;
            min-height: 140px;
        }
        
        .copy-hint {
            position: absolute;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            background: rgba(16, 185, 129, 0.95);
            color: white;
            padding: 8px 20px;
            border-radius: 20px;
            font-size: 0.875rem;
            font-weight: 600;
            opacity: 0;
            pointer-events: none;
            transition: opacity 0.3s;
            z-index: 10;
        }
        
        .copy-hint.show {
            opacity: 1;
        }
        
        /* Content Section */
        .content-section {
            margin-bottom: 48px;
        }
        
        .content-section h2 {
            font-size: 1.5rem;
            font-weight: 700;
            margin-bottom: 16px;
            color: var(--text);
            padding-bottom: 8px;
            border-bottom: 2px solid var(--border);
            display: inline-block;
        }
        
        .content-section h3 {
            font-size: 1.125rem;
            font-weight: 600;
            margin: 24px 0 12px;
            color: var(--text);
        }
        
        .content-section p {
            color: var(--text-secondary);
            margin-bottom: 12px;
            text-align: justify;
        }
        
        .content-section ul, .content-section ol {
            margin-left: 20px;
            margin-bottom: 16px;
            color: var(--text-secondary);
        }
        
        .content-section li {
            margin-bottom: 6px;
        }
        
        /* Table */
        .table-wrapper {
            overflow-x: auto;
            border-radius: 10px;
            border: 1px solid var(--border);
            margin: 20px 0;
        }
        
        table {
            width: 100%;
            border-collapse: collapse;
            font-size: 0.9375rem;
            min-width: 600px;
        }
        
        th {
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            color: white;
            font-weight: 600;
            padding: 12px 16px;
            text-align: left;
        }
        
        td {
            padding: 10px 16px;
            border-bottom: 1px solid var(--border);
            color: var(--text);
        }
        
        tr:nth-child(even) {
            background: var(--bg);
        }
        
        tr:hover {
            background: #eef2ff;
        }
        
        .mars-sample {
            font-family: "Microsoft YaHei", "PingFang SC", sans-serif;
            color: var(--primary);
            font-weight: 500;
        }
        
        /* FAQ */
        .faq-item {
            background: var(--card);
            border: 1px solid var(--border);
            border-radius: 10px;
            padding: 20px;
            margin-bottom: 16px;
            transition: box-shadow 0.2s;
        }
        
        .faq-item:hover {
            box-shadow: var(--shadow);
        }
        
        .faq-item h3 {
            font-size: 1rem;
            font-weight: 600;
            color: var(--text);
            margin: 0 0 8px 0;
        }
        
        .faq-item p {
            color: var(--text-secondary);
            margin: 0;
            font-size: 0.9375rem;
        }
        
        /* Cards Grid */
        .feature-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
            gap: 20px;
            margin: 24px 0;
        }
        
        .feature-card {
            background: var(--card);
            border: 1px solid var(--border);
            border-radius: 12px;
            padding: 24px;
            transition: all 0.2s;
        }
        
        .feature-card:hover {
            transform: translateY(-2px);
            box-shadow: var(--shadow-lg);
            border-color: var(--primary);
        }
        
        .feature-card h4 {
            font-size: 1rem;
            font-weight: 600;
            color: var(--primary);
            margin-bottom: 8px;
        }
        
        .feature-card p {
            font-size: 0.875rem;
            color: var(--text-secondary);
            margin: 0;
        }
        
        /* Footer */
        .page-footer {
            text-align: center;
            padding: 32px 16px;
            color: var(--text-secondary);
            font-size: 0.875rem;
            border-top: 1px solid var(--border);
            margin-top: 48px;
        }
        
        /* Responsive */
        @media (max-width: 640px) {
            .page-header h1 {
                font-size: 1.5rem;
            }
            
            .tool-section {
                padding: 20px;
            }
            
            .mode-selector {
                gap: 8px;
            }
            
            .mode-btn {
                padding: 6px 14px;
                font-size: 0.8125rem;
            }
            
            .action-bar {
                justify-content: center;
            }
            
            .btn {
                flex: 1;
                justify-content: center;
                min-width: 100px;
            }
            
            table {
                font-size: 0.875rem;
            }
            
            th, td {
                padding: 8px 12px;
            }
        }