/* roulang page: index */
:root {
            --primary: #0f766e;
            --primary-hover: #0d9488;
            --accent: #d97706;
            --dark: #0f172a;
            --text-main: #334155;
            --text-light: #64748b;
            --bg-light: #f8fafc;
        }
        html {
            scroll-behavior: smooth;
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
        }
        body {
            color: var(--text-main);
            background-color: #ffffff;
            line-height: 1.7;
        }
        .hero-banner {
            background-image: linear-gradient(to right, rgba(248, 250, 252, 0.96) 35%, rgba(248, 250, 252, 0.85) 65%, rgba(248, 250, 252, 0.7) 100%), url('/assets/images/4731605237e522ce.webp');
            background-size: cover;
            background-position: center;
        }
        .dark-concept-bg {
            background-image: linear-gradient(rgba(15, 23, 42, 0.95), rgba(15, 23, 42, 0.98)), url('/assets/images/3d46c8cbd2f8a2d5.jpg');
            background-size: cover;
            background-position: center;
        }
        details summary::-webkit-details-marker {
            display: none;
        }
        details[open] summary .faq-icon {
            transform: rotate(180deg);
        }