body {
            font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
            background: linear-gradient(135deg, #1e3c72 0%, #2a5298 100%);
            min-height: 100vh;
            padding: 20px;
            color: #333;
        }
        .container {
            max-width: 1500px;
            margin: 0 auto;
        }
        .header {
            text-align: center;
            margin-bottom: 30px;
            color: white;
        }
        .header h1 {
            font-size: 2.5rem;
            margin-bottom: 10px;
            text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
        }
        .header p {
            font-size: 1.1rem;
            opacity: 0.9;
        }
        .main-grid {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 25px;
        }
        @media (max-width: 1024px) {
            .main-grid {
                grid-template-columns: 1fr;
            }
        }
        .card {
            background: white;
            border-radius: 20px;
            padding: 25px;
            box-shadow: 0 15px 40px rgba(0,0,0,0.2);
        }
        .card h2 {
            color: #2a5298;
            margin-bottom: 20px;
            font-size: 1.5rem;
            display: flex;
            align-items: center;
            gap: 10px;
        }
        .input-group {
            margin-bottom: 20px;
        }
        .input-group label {
            display: block;
            font-weight: 600;
            color: #333;
            margin-bottom: 8px;
            font-size: 0.95rem;
        }
        .input-group input,
        .input-group textarea {
            width: 100%;
            padding: 5px 18px;
            border: 2px solid #e0e0e0;
            border-radius: 12px;
            font-size: 1rem;
            font-family: 'Fira Code', monospace;
            transition: all 0.3s ease;
        }
        .input-group input:focus,
        .input-group textarea:focus {
            outline: none;
            border-color: #2a5298;
            box-shadow: 0 0 0 4px rgba(42, 82, 152, 0.1);
        }
        .input-hint {
            font-size: 0.85rem;
            color: #666;
            margin-top: 6px;
        }
        .btn {
            padding: 12px 28px;
            border: none;
            border-radius: 12px;
            font-size: 1rem;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
            display: inline-flex;
            align-items: center;
            gap: 8px;
        }
        .btn-primary {
            background: linear-gradient(135deg, #2a5298, #1e3c72);
            color: white;
        }
        .btn-secondary {
            background: #f0f0f0;
            color: #333;
        }
        .btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 8px 20px rgba(0,0,0,0.2);
        }
        .output-area {
            background: #1e1e1e;
            color: #d4d4d4;
            border-radius: 15px;
            padding: 25px;
            font-family: 'Fira Code', 'Courier New', monospace;
            font-size: 0.9rem;
            line-height: 1.6;
            overflow-x: auto;
            white-space: pre-wrap;
            word-break: break-all;
            max-height: 750px;
            overflow-y: auto;
            position: relative;
        }
        .output-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 15px;
            padding-bottom: 15px;
            border-bottom: 1px solid #333;
        }
        .output-title {
            color: #4ecdc4;
            font-weight: 600;
        }
        .copy-btn {
            background: #4ecdc4;
            color: #1e1e1e;
            padding: 8px 16px;
            border-radius: 8px;
            font-size: 0.85rem;
            border: none;
            cursor: pointer;
            font-weight: 600;
        }
        .copy-btn:hover {
            background: #3db9b2;
        }
        .tag {
            color: #569cd6;
        }
        .attr {
            color: #9cdcfe;
        }
        .value {
            color: #ce9178;
        }
        .comment {
            color: #6a9955;
        }
        .section-divider {
            color: #ffd700;
            font-weight: bold;
            margin: 20px 0;
            display: block;
        }
        .batch-input {
            min-height: 200px;
            resize: vertical;
        }
        .stats {
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            gap: 15px;
            margin-bottom: 15px;
        }
        .stat-box {
            background: linear-gradient(135deg, #f8f9fa, #e9ecef);
            padding: 10px;
            border-radius: 12px;
            text-align: center;
        }
        .stat-value {
            font-size: 2rem;
            font-weight: 800;
            color: #2a5298;
        }
        .stat-label {
            font-size: 0.9rem;
            color: #666;
            margin-top: 5px;
        }
        .tabs {
            display: flex;
            gap: 10px;
            margin-bottom: 20px;
            border-bottom: 2px solid #e0e0e0;
            flex-wrap: wrap;
        }
        .tab {
            padding: 12px 24px;
            background: none;
            border: none;
            cursor: pointer;
            font-size: 1rem;
            font-weight: 600;
            color: #666;
            transition: all 0.3s ease;
            position: relative;
        }
        .tab.active {
            color: #2a5298;
        }
        .tab.active::after {
            content: '';
            position: absolute;
            bottom: -2px;
            left: 0;
            right: 0;
            height: 3px;
            background: #2a5298;
            border-radius: 3px 3px 0 0;
        }
        .tab-content {
            display: none;
        }
        .tab-content.active {
            display: block;
        }
        .success-message {
            position: fixed;
            top: 20px;
            right: 20px;
            background: #4ecdc4;
            color: white;
            padding: 15px 25px;
            border-radius: 12px;
            box-shadow: 0 10px 30px rgba(0,0,0,0.2);
            display: none;
            animation: slideIn 0.3s ease;
            z-index: 1000;
        }
        @keyframes slideIn {
            from { transform: translateX(100%); opacity: 0; }
            to { transform: translateX(0); opacity: 1; }
        }
        .format-example {
            background: #f8f9fa;
            border-left: 4px solid #2a5298;
            padding: 12px;
            margin: 10px 0;
            border-radius: 0 8px 8px 0;
            font-family: 'Fira Code', monospace;
            font-size: 0.85rem;
            color: #555;
        }
        /* Educational Section Styles */
        .edu-section {
            background: white;
            border-radius: 20px;
            padding: 40px;
            margin-top: 40px;
            box-shadow: 0 15px 40px rgba(0,0,0,0.2);
        }
        .edu-section h2 {
            color: #2a5298;
            font-size: 2rem;
            margin-bottom: 30px;
            text-align: center;
        }
        .edu-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 30px;
            margin-bottom: 40px;
        }
        .edu-card {
            background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
            border-radius: 15px;
            padding: 25px;
            border-left: 5px solid #2a5298;
        }
        .edu-card h3 {
            color: #2a5298;
            font-size: 1.3rem;
            margin-bottom: 15px;
            display: flex;
            align-items: center;
            gap: 10px;
        }
        .edu-card h4 {
            color: #1e3c72;
            font-size: 1.1rem;
            margin: 20px 0 10px 0;
        }
        .edu-card p, .edu-card li {
            color: #555;
            line-height: 1.7;
            font-size: 0.95rem;
        }
        .edu-card ul {
            margin-left: 20px;
            margin-top: 10px;
        }
        .edu-card li {
            margin-bottom: 8px;
        }
        .port-table {
            width: 100%;
            border-collapse: collapse;
            margin: 20px 0;
            font-size: 0.9rem;
        }
        .port-table th, .port-table td {
            padding: 12px;
            text-align: left;
            border-bottom: 1px solid #dee2e6;
        }
        .port-table th {
            background: #2a5298;
            color: white;
            font-weight: 600;
        }
        .port-table tr:hover {
            background: #f8f9fa;
        }
        .port-587 { color: #28a745; font-weight: bold; }
        .port-465 { color: #fd7e14; font-weight: bold; }
        .port-25 { color: #dc3545; font-weight: bold; }
        .port-2525 { color: #6c757d; font-weight: bold; }
        .faq-item {
            margin-bottom: 25px;
            padding-bottom: 25px;
            border-bottom: 1px solid #e9ecef;
        }
        .faq-item:last-child {
            border-bottom: none;
        }
        .faq-question {
            font-weight: 700;
            color: #2a5298;
            font-size: 1.1rem;
            margin-bottom: 10px;
            cursor: pointer;
        }
        .faq-answer {
            color: #555;
            line-height: 1.7;
            padding-left: 20px;
            border-left: 3px solid #4ecdc4;
        }
        .mechanism-flow {
            background: #1e1e1e;
            color: #d4d4d4;
            padding: 20px;
            border-radius: 10px;
            font-family: 'Fira Code', monospace;
            font-size: 0.85rem;
            line-height: 1.8;
            margin: 20px 0;
            overflow-x: auto;
        }
        .highlight-box {
            background: linear-gradient(135deg, #fff3cd 0%, #ffeaa7 100%);
            border-left: 5px solid #f39c12;
            padding: 20px;
            border-radius: 0 10px 10px 0;
            margin: 20px 0;
        }
        .highlight-box strong {
            color: #d35400;
        }
        .tls-badge {
            display: inline-block;
            background: #28a745;
            color: white;
            padding: 4px 8px;
            border-radius: 4px;
            font-size: 0.75rem;
            font-weight: 600;
            margin-left: 8px;
        }
        .rfc-reference {
            background: #e3f2fd;
            padding: 15px;
            border-radius: 8px;
            margin: 15px 0;
            font-size: 0.9rem;
            color: #1565c0;
        }
        .rfc-reference strong {
            color: #0d47a1;
        }
        @media (max-width: 768px) {
            .edu-grid {
                grid-template-columns: 1fr;
            }
            .edu-section {
                padding: 20px;
            }
            .tabs {
                flex-direction: column;
            }
            .tab {
                width: 100%;
                text-align: center;
            }
        }