:root {
            --primary-color: #007bff;
            --secondary-color: #6c757d;
            --success-color: #28a745;
            --warning-color: #ffc107;
            --danger-color: #dc3545;
            --info-color: #17a2b8;
        }

        body {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: #343a40;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            transition: all 0.3s ease;
            min-height: 100vh;
        }

        .main-container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 20px;
        }

        .content-card {
            background: rgba(255, 255, 255, 0.95);
            backdrop-filter: blur(10px);
            border-radius: 15px;
            box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
            padding: 30px;
            margin-bottom: 20px;
            transition: all 0.3s ease;
        }

        .hero-section {
            text-align: center;
            padding: 40px 0;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            border-radius: 15px;
            margin-bottom: 30px;
        }

        .hero-title {
            font-size: 3rem;
            font-weight: bold;
            margin-bottom: 20px;
            text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
        }

        .hero-subtitle {
            font-size: 1.2rem;
            opacity: 0.9;
        }

        .nav-pills {
            background: rgba(255, 255, 255, 0.1);
            border-radius: 10px;
            padding: 10px;
            margin-bottom: 30px;
        }

        .nav-pills .nav-link {
            border-radius: 8px;
            margin: 0 5px;
            transition: all 0.3s ease;
        }

        .nav-pills .nav-link.active {
            background: var(--primary-color);
            box-shadow: 0 4px 15px rgba(0, 123, 255, 0.3);
        }

        .tool-card {
            border: none;
            border-radius: 12px;
            transition: all 0.3s ease;
            height: 100%;
            background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
        }

        .tool-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 10px 25px rgba(0, 0, 0, 0.15);
        }

        .tool-icon {
            font-size: 3rem;
            margin-bottom: 15px;
        }

        .difficulty-badge {
            position: absolute;
            top: 15px;
            right: 15px;
            border-radius: 20px;
            padding: 5px 12px;
            font-size: 0.8rem;
            font-weight: bold;
        }

        .difficulty-easy {
            background: var(--success-color);
            color: white;
        }

        .difficulty-medium {
            background: var(--warning-color);
            color: black;
        }

        .difficulty-hard {
            background: var(--danger-color);
            color: white;
        }

        .code-block {
            background: #2d3748;
            color: #e2e8f0;
            border-radius: 8px;
            padding: 20px;
            margin: 15px 0;
            position: relative;
            overflow-x: auto;
        }

        .copy-btn {
            position: absolute;
            top: 10px;
            right: 10px;
            background: rgba(255, 255, 255, 0.1);
            border: none;
            color: white;
            padding: 5px 10px;
            border-radius: 5px;
            cursor: pointer;
            transition: all 0.3s ease;
        }

        .copy-btn:hover {
            background: rgba(255, 255, 255, 0.2);
        }

        .comparison-table {
            background: white;
            border-radius: 10px;
            overflow: hidden;
            box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
        }

        .comparison-table th {
            background: var(--primary-color);
            color: white;
            border: none;
            padding: 15px;
        }

        .comparison-table td {
            padding: 12px 15px;
            border-bottom: 1px solid #e9ecef;
        }

        .feature-icon {
            color: var(--success-color);
            margin-right: 8px;
        }

        .warning-box {
            background: linear-gradient(135deg, #fff3cd 0%, #ffeaa7 100%);
            border-left: 4px solid var(--warning-color);
            padding: 15px;
            border-radius: 8px;
            margin: 20px 0;
        }

        .info-box {
            background: linear-gradient(135deg, #d1ecf1 0%, #bee5eb 100%);
            border-left: 4px solid var(--info-color);
            padding: 15px;
            border-radius: 8px;
            margin: 20px 0;
        }

        .success-box {
            background: linear-gradient(135deg, #d4edda 0%, #c3e6cb 100%);
            border-left: 4px solid var(--success-color);
            padding: 15px;
            border-radius: 8px;
            margin: 20px 0;
        }

        /* Dark mode styles */
        .dark-mode {
            background: linear-gradient(135deg, #2c3e50 0%, #34495e 100%);
            color: #ecf0f1;
        }

        .dark-mode .content-card {
            background: rgba(52, 73, 94, 0.95);
            color: #ecf0f1;
        }

        .dark-mode .tool-card {
            background: linear-gradient(135deg, #34495e 0%, #2c3e50 100%);
            color: #ecf0f1;
        }

        .dark-mode .comparison-table {
            background: #34495e;
            color: #ecf0f1;
        }

        .dark-mode .comparison-table td {
            border-bottom-color: #4a5f7a;
        }

        .floating-toc {
            position: fixed;
            right: 20px;
            top: 50%;
            transform: translateY(-50%);
            background: rgba(255, 255, 255, 0.95);
            border-radius: 10px;
            padding: 15px;
            box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
            max-height: 400px;
            overflow-y: auto;
            z-index: 1000;
            display: none;
        }

        .floating-toc.show {
            display: block;
        }

        .toc-item {
            display: block;
            color: var(--primary-color);
            text-decoration: none;
            padding: 5px 0;
            font-size: 0.9rem;
            transition: all 0.3s ease;
        }

        .toc-item:hover {
            color: var(--secondary-color);
            padding-left: 10px;
        }

        @media (max-width: 768px) {
            .hero-title {
                font-size: 2rem;
            }

            .floating-toc {
                display: none !important;
            }

            .main-container {
                padding: 10px;
            }
        }

        .scroll-to-top {
            position: fixed;
            bottom: 20px;
            right: 20px;
            background: var(--primary-color);
            color: white;
            border: none;
            border-radius: 50%;
            width: 50px;
            height: 50px;
            font-size: 1.2rem;
            cursor: pointer;
            transition: all 0.3s ease;
            opacity: 0;
            visibility: hidden;
        }

        .scroll-to-top.show {
            opacity: 1;
            visibility: visible;
        }

        .scroll-to-top:hover {
            background: var(--secondary-color);
            transform: translateY(-3px);
        }

        #modeSwitch {
            border-radius: 50%;
            width: 50px;
            height: 50px;
            display: flex;
            align-items: center;
            justify-content: center;
            transition: all 0.3s ease;
        }

        #modeSwitch:hover {
            transform: scale(1.1);
        }