/* roulang page: index */
:root {
            --bg-primary: #0d1117;
            --bg-secondary: #161b22;
            --brand-green: #10b981;
            --brand-cyan: #06b6d4;
            --text-main: #f8fafc;
            --text-muted: #94a3b8;
            --border-line: rgba(255, 255, 255, 0.08);
        }
        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
            scroll-behavior: smooth;
        }
        body {
            background-color: var(--bg-primary);
            color: var(--text-main);
            font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif;
            line-height: 1.75;
            overflow-x: hidden;
        }
        .section-separator {
            border-bottom: 1px solid var(--border-line);
        }
        .card-hover {
            transition: transform 0.25s ease-in-out, border-color 0.25s ease-in-out, box-shadow 0.25s ease-in-out;
        }
        .card-hover:hover {
            transform: translateY(-2px);
            border-color: rgba(16, 185, 129, 0.4);
            box-shadow: 0 10px 25px -5px rgba(16, 185, 129, 0.08);
        }
        .hero-slide {
            display: none;
            opacity: 0;
            transition: opacity 0.5s ease-in-out;
        }
        .hero-slide.active {
            display: block;
            opacity: 1;
        }
        .faq-content {
            max-height: 0;
            overflow: hidden;
            transition: max-height 0.35s ease-in-out;
        }
        .faq-content.open {
            max-height: 200px;
        }