:root {
            --primary-color: #0056b3;
            --secondary-color: #28a745;
            --dark-color: #212529;
            --light-color: #f8f9fa;
            --accent-color: #ffc107;
        }
        body {
            font-family: "Microsoft YaHei", "Segoe UI", sans-serif;
            color: #333;
            overflow-x: hidden;
        }
        .navbar-brand {
            font-weight: 700;
            font-size: 1.8rem;
            color: var(--primary-color) !important;
        }
        .nav-link {
            font-weight: 500;
            transition: color 0.3s;
        }
        .nav-link:hover, .nav-link.active {
            color: var(--secondary-color) !important;
        }
        .hero-section {
            background: linear-gradient(rgba(0, 84, 179, 0.85), rgba(40, 167, 69, 0.8)), url('https://images.unsplash.com/photo-1620712943543-bcc4688e7485?ixlib=rb-4.0.3&auto=format&fit=crop&w=1920&q=80') no-repeat center center/cover;
            color: white;
            padding: 150px 0;
        }
        .section-title {
            position: relative;
            padding-bottom: 15px;
            margin-bottom: 40px;
            font-weight: 700;
            color: var(--dark-color);
        }
        .section-title:after {
            content: '';
            position: absolute;
            bottom: 0;
            left: 0;
            width: 60px;
            height: 4px;
            background-color: var(--secondary-color);
        }
        .text-center .section-title:after {
            left: 50%;
            transform: translateX(-50%);
        }
        .card-hover {
            transition: transform 0.3s, box-shadow 0.3s;
            height: 100%;
        }
        .card-hover:hover {
            transform: translateY(-10px);
            box-shadow: 0 15px 30px rgba(0, 0, 0, 0.1) !important;
        }
        .icon-box {
            width: 70px;
            height: 70px;
            border-radius: 50%;
            background-color: rgba(0, 86, 179, 0.1);
            display: flex;
            align-items: center;
            justify-content: center;
            margin-bottom: 20px;
            font-size: 2rem;
            color: var(--primary-color);
        }
        .btn-primary {
            background-color: var(--primary-color);
            border-color: var(--primary-color);
            padding: 10px 30px;
            font-weight: 600;
            transition: all 0.3s;
        }
        .btn-primary:hover {
            background-color: #004494;
            border-color: #004494;
            transform: scale(1.05);
        }
        .btn-success {
            background-color: var(--secondary-color);
            border-color: var(--secondary-color);
            padding: 10px 30px;
            font-weight: 600;
            transition: all 0.3s;
        }
        .btn-success:hover {
            background-color: #218838;
            border-color: #218838;
            transform: scale(1.05);
        }
        footer {
            background-color: var(--dark-color);
            color: var(--light-color);
        }
        .flink {
            color: #ddd;
            text-decoration: none;
            transition: color 0.3s;
            margin: 5px 10px;
            display: inline-block;
        }
        .flink:hover {
            color: var(--secondary-color);
            text-decoration: underline;
        }
        .back-to-top {
            position: fixed;
            bottom: 30px;
            right: 30px;
            width: 50px;
            height: 50px;
            border-radius: 50%;
            background-color: var(--primary-color);
            color: white;
            display: flex;
            align-items: center;
            justify-content: center;
            text-decoration: none;
            font-size: 1.5rem;
            z-index: 999;
            opacity: 0;
            transition: opacity 0.3s;
        }
        .back-to-top.show {
            opacity: 1;
        }
        .product-img {
            height: 200px;
            object-fit: cover;
        }
        .timeline {
            position: relative;
            padding-left: 30px;
        }
        .timeline:before {
            content: '';
            position: absolute;
            left: 0;
            top: 0;
            bottom: 0;
            width: 3px;
            background-color: var(--primary-color);
        }
        .timeline-item {
            position: relative;
            margin-bottom: 30px;
        }
        .timeline-item:before {
            content: '';
            position: absolute;
            left: -36px;
            top: 5px;
            width: 15px;
            height: 15px;
            border-radius: 50%;
            background-color: var(--secondary-color);
            border: 3px solid white;
            box-shadow: 0 0 0 3px var(--primary-color);
        }
        @media (max-width: 768px) {
            .hero-section {
                padding: 100px 0;
            }
            .display-4 {
                font-size: 2.5rem;
            }
        }