:root {
            --primary-color: #1a5276;
            --secondary-color: #f39c12;
            --accent-color: #e74c3c;
            --text-color: #2c3e50;
            --light-bg: #f8f9fa;
            --dark-bg: #2c3e50;
        }
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            line-height: 1.7;
            color: var(--text-color);
            background-color: var(--light-bg);
        }
        .navbar-brand {
            font-weight: 800;
            font-size: 1.8rem;
            color: var(--primary-color) !important;
            text-shadow: 1px 1px 2px rgba(0,0,0,0.1);
        }
        .nav-link {
            font-weight: 600;
            transition: all 0.3s ease;
        }
        .nav-link:hover {
            color: var(--secondary-color) !important;
            transform: translateY(-2px);
        }
        .hero-section {
            background: linear-gradient(135deg, var(--primary-color) 0%, #2980b9 100%);
            color: white;
            padding: 4rem 0;
            margin-bottom: 3rem;
            border-radius: 0 0 20px 20px;
        }
        .section-title {
            color: var(--primary-color);
            border-left: 5px solid var(--secondary-color);
            padding-left: 15px;
            margin: 2.5rem 0 1.5rem;
            font-weight: 700;
        }
        .subsection-title {
            color: var(--dark-bg);
            margin: 2rem 0 1rem;
            font-weight: 600;
        }
        .content-card {
            background: white;
            border-radius: 10px;
            box-shadow: 0 5px 15px rgba(0,0,0,0.05);
            padding: 2rem;
            margin-bottom: 2rem;
            transition: transform 0.3s ease, box-shadow 0.3s ease;
            border-top: 4px solid var(--secondary-color);
        }
        .content-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 10px 25px rgba(0,0,0,0.1);
        }
        .feature-icon {
            font-size: 2.5rem;
            color: var(--secondary-color);
            margin-bottom: 1rem;
        }
        .highlight-text {
            background: linear-gradient(120deg, #f6d365 0%, #fda085 100%);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            font-weight: 700;
        }
        .key-point {
            background-color: rgba(243, 156, 18, 0.1);
            border-left: 4px solid var(--secondary-color);
            padding: 1rem 1.5rem;
            margin: 1.5rem 0;
            border-radius: 0 8px 8px 0;
        }
        .chess-board {
            width: 100%;
            max-width: 500px;
            margin: 2rem auto;
            border: 3px solid var(--primary-color);
            border-radius: 5px;
            overflow: hidden;
        }
        .chess-square {
            width: 12.5%;
            padding-bottom: 12.5%;
            float: left;
            position: relative;
        }
        .light-square {
            background-color: #f0d9b5;
        }
        .dark-square {
            background-color: #b58863;
        }
        footer {
            background-color: var(--dark-bg);
            color: white;
            padding: 3rem 0 2rem;
            margin-top: 4rem;
        }
        .footer-heading {
            color: var(--secondary-color);
            margin-bottom: 1.5rem;
            font-weight: 600;
        }
        .social-icons a {
            color: white;
            font-size: 1.5rem;
            margin-right: 1rem;
            transition: color 0.3s ease;
        }
        .social-icons a:hover {
            color: var(--secondary-color);
        }
        .back-to-top {
            position: fixed;
            bottom: 30px;
            right: 30px;
            background-color: var(--primary-color);
            color: white;
            width: 50px;
            height: 50px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 1.5rem;
            box-shadow: 0 3px 10px rgba(0,0,0,0.2);
            transition: all 0.3s ease;
            z-index: 1000;
        }
        .back-to-top:hover {
            background-color: var(--secondary-color);
            transform: translateY(-5px);
        }
        @media (max-width: 768px) {
            .hero-section {
                padding: 2.5rem 0;
            }
            .content-card {
                padding: 1.5rem;
            }
            .section-title {
                font-size: 1.5rem;
            }
        }