/* roulang page: index */
:root {
            --brand-deep: #0F3D3E;
            --brand-emerald: #105652;
            --brand-amber: #D49B35;
            --brand-dark: #1E293B;
            --brand-bg: #F8FAFC;
        }
        body {
            font-family: system-ui, -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif;
            background-color: var(--brand-bg);
            color: #334155;
            line-height: 1.75;
            -webkit-font-smoothing: antialiased;
        }
        h1, h2, h3, h4, h5, h6 {
            line-height: 1.3;
            letter-spacing: -0.015em;
        }
        .hero-bg-overlay {
            background: linear-gradient(135deg, rgba(15, 61, 62, 0.95) 0%, rgba(16, 86, 82, 0.88) 100%);
        }
        .tab-btn.active {
            background-color: var(--brand-emerald);
            color: #ffffff;
            border-color: var(--brand-emerald);
        }
        .faq-content {
            transition: max-height 0.3s ease-out, opacity 0.3s ease-out;
            max-height: 0;
            overflow: hidden;
            opacity: 0;
        }
        .faq-item.open .faq-content {
            max-height: 300px;
            opacity: 1;
        }
        .faq-item.open .faq-icon {
            transform: rotate(180deg);
        }
        .btn-floating {
            transform: translateY(100px);
            opacity: 0;
            transition: all 0.3s ease-in-out;
        }
        .btn-floating.visible {
            transform: translateY(0);
            opacity: 1;
        }