/* roulang page: index */
:root {
            --primary: #00C076;
            --primary-hover: #059669;
            --accent-blue: #0EA5E9;
            --accent-orange: #F59E0B;
            --bg-body: #F8FAFC;
            --bg-dark: #0F172A;
            --text-main: #1E293B;
            --text-light: #64748B;
            --white: #FFFFFF;
            --border: #E2E8F0;
            --radius: 12px;
            --shadow: 0 4px 20px -2px rgba(15, 23, 42, 0.05);
        }

        * { box-sizing: border-box; margin: 0; padding: 0; }
        body { font-family: system-ui, -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif; line-height: 1.75; color: var(--text-main); background-color: var(--bg-body); }
        .container { max-width: 1240px; margin: 0 auto; padding: 0 20px; }
        
        /* Header */
        header { background: var(--white); border-bottom: 1px solid var(--border); position: sticky; top: 0; z-index: 1000; }
        .top-bar { font-size: 0.85rem; padding: 8px 0; border-bottom: 1px solid var(--border); color: var(--text-light); text-align: center; }
        nav { display: flex; justify-content: space-between; align-items: center; padding: 15px 0; }
        .logo { font-weight: 800; font-size: 1.4rem; color: var(--primary); text-decoration: none; display: flex; align-items: center; gap: 8px; }
        .nav-links a { text-decoration: none; color: var(--text-main); font-weight: 500; margin-left: 25px; transition: color 0.3s; }
        .nav-links a:hover { color: var(--primary); }
        .btn-primary { background: var(--primary); color: var(--white); padding: 10px 24px; border-radius: var(--radius); text-decoration: none; font-weight: 600; }

        /* Sections */
        section { padding: 80px 0; }
        h2 { font-size: 2.5rem; margin-bottom: 20px; text-align: center; }
        .section-desc { text-align: center; color: var(--text-light); max-width: 700px; margin: 0 auto 50px; font-size: 1.1rem; }

        /* Banner */
        .section-banner { padding: 100px 0; background: linear-gradient(135deg, #F8FAFC 0%, #E2E8F0 100%); }
        .banner-content { display: flex; align-items: center; gap: 60px; }
        .banner-text { flex: 1; }
        .banner-img { flex: 1; border-radius: var(--radius); overflow: hidden; box-shadow: var(--shadow); }

        /* Advantages Grid */
        .adv-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
        .card { background: var(--white); padding: 30px; border-radius: var(--radius); border: 1px solid var(--border); transition: transform 0.3s; }
        .card:hover { transform: translateY(-5px); box-shadow: var(--shadow); }

        /* Dark Section */
        .section-dark-concept { background: var(--bg-dark); color: var(--white); }
        .section-dark-concept .section-desc { color: #94A3B8; }

        /* Metrics */
        .section-metrics { background: var(--primary); color: var(--white); padding: 40px 0; }
        .metrics-grid { display: grid; grid-template-columns: repeat(4, 1fr); text-align: center; gap: 20px; }
        .metric-item b { display: block; font-size: 2.5rem; }

        /* FAQ */
        details { background: var(--white); padding: 20px; margin-bottom: 15px; border-radius: var(--radius); border: 1px solid var(--border); }
        summary { font-weight: 600; cursor: pointer; list-style: none; }

        footer { background: var(--bg-dark); color: #94A3B8; padding: 60px 0 20px; text-align: center; }
        
        @media (max-width: 768px) {
            .banner-content { flex-direction: column; }
            .adv-grid { grid-template-columns: 1fr; }
            .metrics-grid { grid-template-columns: repeat(2, 1fr); gap: 40px; }
        }