:root {
            --primary-blue: #1e40af;
            --ice-blue: #38bdf8;
            --frost-white: #f0f9ff;
            --dark-blue: #1e3a8a;
            --accent-purple: #7e22ce;
        }
        body {
            font-family: 'Segoe UI', system-ui, sans-serif;
            background: linear-gradient(135deg, var(--frost-white) 0%, #e0f2fe 100%);
            color: #1f2937;
            line-height: 1.7;
        }
        .logo-brand {
            font-family: 'Impact', 'Arial Black', sans-serif;
            font-size: 2.2rem;
            background: linear-gradient(45deg, var(--primary-blue), var(--ice-blue));
            -webkit-background-clip: text;
            background-clip: text;
            color: transparent;
            font-weight: 900;
            text-transform: uppercase;
            letter-spacing: 2px;
        }
        .nav-custom {
            background: rgba(255, 255, 255, 0.95);
            backdrop-filter: blur(10px);
            border-bottom: 3px solid var(--ice-blue);
            box-shadow: 0 4px 20px rgba(30, 64, 175, 0.1);
        }
        .hero-section {
            background: linear-gradient(135deg, var(--primary-blue) 0%, var(--accent-purple) 100%);
            color: white;
            padding: 4rem 0;
            border-radius: 0 0 30px 30px;
            margin-bottom: 3rem;
        }
        .content-card {
            background: white;
            border-radius: 20px;
            padding: 2.5rem;
            margin-bottom: 2rem;
            box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
            border: 1px solid rgba(56, 189, 248, 0.2);
            transition: transform 0.3s ease, box-shadow 0.3s ease;
        }
        .content-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 20px 40px rgba(0, 0, 0, 0.12);
        }
        h1, h2, h3 {
            color: var(--dark-blue);
            font-weight: 700;
            margin-bottom: 1.5rem;
        }
        h1 {
            font-size: 2.8rem;
            text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.1);
        }
        h2 {
            font-size: 2.2rem;
            border-left: 5px solid var(--ice-blue);
            padding-left: 1rem;
            margin-top: 2.5rem;
        }
        h3 {
            font-size: 1.8rem;
            color: var(--primary-blue);
            margin-top: 2rem;
        }
        .key-term {
            background: linear-gradient(120deg, var(--ice-blue) 0%, var(--ice-blue) 100%);
            background-position: 0 88%;
            background-repeat: no-repeat;
            background-size: 100% 0.3em;
            font-weight: 700;
            padding-bottom: 2px;
        }
        .highlight-box {
            background: linear-gradient(135deg, #dbeafe 0%, #e0f2fe 100%);
            border-left: 4px solid var(--ice-blue);
            padding: 1.5rem;
            border-radius: 0 12px 12px 0;
            margin: 2rem 0;
        }
        .game-feature {
            background: white;
            border-radius: 15px;
            padding: 1.5rem;
            margin: 1rem 0;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
            border: 1px solid rgba(56, 189, 248, 0.3);
        }
        .icon-feature {
            font-size: 2.5rem;
            color: var(--ice-blue);
            margin-bottom: 1rem;
        }
        img {
            border-radius: 15px;
            box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
            transition: transform 0.3s ease;
            width: 100%;
            height: auto;
        }
        img:hover {
            transform: scale(1.02);
        }
        footer {
            background: var(--dark-blue);
            color: white;
            padding: 3rem 0;
            margin-top: 4rem;
        }
        .toc-item {
            padding: 0.5rem 0;
            border-bottom: 1px solid rgba(56, 189, 248, 0.2);
        }
        .toc-item:last-child {
            border-bottom: none;
        }
        .nav-link {
            color: var(--dark-blue);
            font-weight: 600;
            transition: color 0.3s ease;
        }
        .nav-link:hover {
            color: var(--ice-blue);
        }
        @media (max-width: 768px) {
            h1 {
                font-size: 2.2rem;
            }
            h2 {
                font-size: 1.8rem;
            }
            h3 {
                font-size: 1.5rem;
            }
            .content-card {
                padding: 1.5rem;
            }
            .logo-brand {
                font-size: 1.8rem;
            }
        }
        .float-animation {
            animation: float 6s ease-in-out infinite;
        }
        @keyframes float {
            0% { transform: translateY(0px); }
            50% { transform: translateY(-10px); }
            100% { transform: translateY(0px); }
        }