:root {
            --primary-color: #0056a8;
            --secondary-color: #28a745;
            --dark-color: #212529;
            --light-color: #f8f9fa;
            --accent-color: #ff6b00;
        }
        body {
            font-family: "Microsoft YaHei", "Segoe UI", sans-serif;
            color: #333;
            line-height: 1.8;
            overflow-x: hidden;
        }
        .navbar-brand {
            font-weight: 700;
            font-size: 1.8rem;
        }
        .navbar {
            box-shadow: 0 2px 15px rgba(0, 0, 0, 0.08);
            background-color: rgba(255, 255, 255, 0.97) !important;
            transition: all 0.3s ease;
        }
        .navbar-nav .nav-link {
            font-weight: 500;
            padding: 0.5rem 1.2rem !important;
            position: relative;
        }
        .navbar-nav .nav-link::after {
            content: '';
            position: absolute;
            width: 0;
            height: 2px;
            bottom: 0;
            left: 1.2rem;
            background-color: var(--primary-color);
            transition: width 0.3s;
        }
        .navbar-nav .nav-link:hover::after,
        .navbar-nav .nav-link.active::after {
            width: calc(100% - 2.4rem);
        }
        .hero-section {
            background: linear-gradient(rgba(0, 50, 100, 0.85), rgba(0, 30, 70, 0.9)), url('https://images.unsplash.com/photo-1518709268805-4e9042af2176?ixlib=rb-4.0.3&auto=format&fit=crop&w=1920&q=80') center/cover no-repeat;
            color: white;
            padding: 180px 0 120px;
        }
        .section-title {
            position: relative;
            padding-bottom: 20px;
            margin-bottom: 50px;
            font-weight: 700;
            color: var(--dark-color);
        }
        .section-title::after {
            content: '';
            position: absolute;
            left: 0;
            bottom: 0;
            width: 70px;
            height: 4px;
            background: linear-gradient(to right, var(--primary-color), var(--secondary-color));
        }
        .text-center .section-title::after {
            left: 50%;
            transform: translateX(-50%);
        }
        .card-hover {
            transition: transform 0.3s ease, box-shadow 0.3s ease;
            border: none;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
            height: 100%;
        }
        .card-hover:hover {
            transform: translateY(-10px);
            box-shadow: 0 15px 30px rgba(0, 0, 0, 0.1);
        }
        .icon-box {
            width: 70px;
            height: 70px;
            background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            margin: 0 auto 25px;
            color: white;
            font-size: 1.8rem;
        }
        .btn-primary {
            background: linear-gradient(to right, var(--primary-color), #007bff);
            border: none;
            padding: 12px 30px;
            border-radius: 30px;
            font-weight: 500;
            transition: all 0.3s;
        }
        .btn-primary:hover {
            background: linear-gradient(to right, #004a8f, var(--primary-color));
            transform: scale(1.05);
        }
        .stat-number {
            font-size: 3rem;
            font-weight: 700;
            background: linear-gradient(to right, var(--primary-color), var(--secondary-color));
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            line-height: 1;
        }
        .contact-info-box {
            background: white;
            padding: 30px;
            border-radius: 15px;
            box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
            transition: transform 0.3s;
            height: 100%;
        }
        .contact-info-box:hover {
            transform: translateY(-5px);
        }
        .flink {
            display: inline-block;
            padding: 8px 20px;
            margin: 5px 10px 5px 0;
            background-color: #f1f8ff;
            border-radius: 50px;
            color: var(--primary-color);
            text-decoration: none;
            border: 1px solid #d1e7ff;
            transition: all 0.3s;
        }
        .flink:hover {
            background-color: var(--primary-color);
            color: white;
            transform: translateY(-3px);
        }
        footer {
            background-color: var(--dark-color);
            color: #adb5bd;
            padding-top: 60px;
        }
        footer a {
            color: #dee2e6;
            text-decoration: none;
            transition: color 0.3s;
        }
        footer a:hover {
            color: white;
        }
        .back-to-top {
            position: fixed;
            bottom: 30px;
            right: 30px;
            width: 50px;
            height: 50px;
            background-color: var(--primary-color);
            color: white;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 1.2rem;
            opacity: 0;
            visibility: hidden;
            transition: all 0.4s;
            z-index: 999;
        }
        .back-to-top.active {
            opacity: 1;
            visibility: visible;
        }
        .back-to-top:hover {
            background-color: #004085;
            color: white;
        }
        @media (max-width: 768px) {
            .hero-section {
                padding: 120px 0 80px;
            }
            .section-title {
                font-size: 1.8rem;
            }
            .stat-number {
                font-size: 2.5rem;
            }
        }