:root {
            --primary-color: #1a365d;
            --secondary-color: #2d3748;
            --accent-color: #3182ce;
            --light-color: #f7fafc;
            --dark-color: #2d3748;
            --transition: all 0.3s ease;
        }
        body {
            font-family: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
            color: #333;
            overflow-x: hidden;
        }
        .hero-section {
            background: linear-gradient(135deg, var(--primary-color) 0%, var(--accent-color) 100%);
            color: white;
            padding: 100px 0;
            position: relative;
            overflow: hidden;
        }
        .hero-section::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1440 320"><path fill="rgba(255,255,255,0.05)" d="M0,224L48,213.3C96,203,192,181,288,181.3C384,181,480,203,576,192C672,181,768,139,864,128C960,117,1056,139,1152,149.3C1248,160,1344,160,1392,160L1440,160L1440,320L1392,320C1344,320,1248,320,1152,320C1056,320,960,320,864,320C768,320,672,320,576,320C480,320,384,320,288,320C192,320,96,320,48,320L0,320Z"></path></svg>') no-repeat bottom center;
            background-size: cover;
        }
        .section-title {
            position: relative;
            padding-bottom: 15px;
            margin-bottom: 40px;
            text-align: center;
        }
        .section-title::after {
            content: '';
            position: absolute;
            bottom: 0;
            left: 50%;
            transform: translateX(-50%);
            width: 80px;
            height: 4px;
            background: var(--accent-color);
        }
        .service-card {
            transition: var(--transition);
            border: none;
            box-shadow: 0 5px 15px rgba(0,0,0,0.08);
            height: 100%;
            border-radius: 10px;
            overflow: hidden;
        }
        .service-card:hover {
            transform: translateY(-10px);
            box-shadow: 0 15px 30px rgba(0,0,0,0.15);
        }
        .service-icon {
            width: 70px;
            height: 70px;
            background: var(--accent-color);
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            margin: 0 auto 20px;
            color: white;
            font-size: 28px;
        }
        .nav-link {
            position: relative;
            font-weight: 500;
        }
        .nav-link::after {
            content: '';
            position: absolute;
            bottom: 5px;
            left: 50%;
            transform: translateX(-50%) scaleX(0);
            width: 20px;
            height: 2px;
            background: var(--accent-color);
            transition: var(--transition);
        }
        .nav-link:hover::after, .nav-link.active::after {
            transform: translateX(-50%) scaleX(1);
        }
        .footer {
            background: var(--secondary-color);
            color: white;
            padding: 60px 0 20px;
        }
        .flink {
            display: inline-block;
            padding: 8px 15px;
            margin: 5px;
            background: rgba(255,255,255,0.1);
            border-radius: 5px;
            color: #ddd;
            text-decoration: none;
            transition: var(--transition);
            border: 1px solid transparent;
        }
        .flink:hover {
            background: transparent;
            color: white;
            border-color: var(--accent-color);
            text-decoration: none;
        }
        .contact-info i {
            width: 40px;
            color: var(--accent-color);
        }
        .back-to-top {
            position: fixed;
            bottom: 30px;
            right: 30px;
            width: 50px;
            height: 50px;
            background: var(--accent-color);
            color: white;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            text-decoration: none;
            opacity: 0;
            visibility: hidden;
            transition: var(--transition);
            z-index: 1000;
        }
        .back-to-top.show {
            opacity: 1;
            visibility: visible;
        }
        .back-to-top:hover {
            background: var(--primary-color);
            color: white;
        }
        .case-study-img {
            height: 250px;
            object-fit: cover;
            transition: var(--transition);
        }
        .case-item:hover .case-study-img {
            transform: scale(1.05);
        }
        .news-card {
            transition: var(--transition);
            height: 100%;
        }
        .news-card:hover {
            box-shadow: 0 10px 25px rgba(0,0,0,0.1);
        }
        .timeline {
            position: relative;
            padding-left: 30px;
        }
        .timeline::before {
            content: '';
            position: absolute;
            left: 0;
            top: 0;
            bottom: 0;
            width: 2px;
            background: var(--accent-color);
        }
        .timeline-item {
            position: relative;
            margin-bottom: 30px;
        }
        .timeline-item::before {
            content: '';
            position: absolute;
            left: -36px;
            top: 5px;
            width: 12px;
            height: 12px;
            border-radius: 50%;
            background: var(--accent-color);
            border: 3px solid white;
            box-shadow: 0 0 0 3px var(--accent-color);
        }
        @media (max-width: 768px) {
            .hero-section {
                padding: 60px 0;
            }
            .display-4 {
                font-size: 2.2rem;
            }
        }