/* roulang page: index */
:root {
            --primary: #0052FF;
            --primary-hover: #0043D6;
            --accent: #00E599;
            --bg-light: #F8FAFC;
            --text-main: #0F172A;
            --text-muted: #64748B;
            --border-color: #E2E8F0;
        }
        * {
            box-sizing: border-box;
            scroll-behavior: smooth;
        }
        body {
            font-family: system-ui, -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif;
            background-color: var(--bg-light);
            color: var(--text-main);
            line-height: 1.75;
            overflow-x: hidden;
        }
        .container-custom {
            max-width: 1280px;
            margin-left: auto;
            margin-right: auto;
            padding-left: 1.5rem;
            padding-right: 1.5rem;
        }
        .card-custom {
            background: #FFFFFF;
            border: 1px solid rgba(226, 232, 240, 0.8);
            box-shadow: 0 4px 20px -2px rgba(0, 0, 0, 0.05);
            border-radius: 12px;
            transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
        }
        .card-custom:hover {
            transform: translateY(-4px);
            box-shadow: 0 12px 30px -4px rgba(0, 82, 255, 0.08);
            border-color: rgba(0, 82, 255, 0.3);
        }
        .code-block {
            background-color: #0d131f;
            border: 1px solid #1e293b;
            font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
        }
        .nav-link {
            transition: color 0.2s ease;
            position: relative;
        }
        .nav-link:hover {
            color: var(--primary);
        }
        .btn-primary {
            background-color: var(--primary);
            color: #FFFFFF;
            transition: all 0.2s ease;
        }
        .btn-primary:hover {
            background-color: var(--primary-hover);
            box-shadow: 0 4px 14px rgba(0, 82, 255, 0.35);
        }