/* roulang page: index */
:root {
            --bg-main: #0B0F19;
            --bg-card: rgba(17, 24, 39, 0.78);
            --border-glow: rgba(56, 189, 248, 0.22);
            --primary-glow: #38BDF8;
            --text-high: #F9FAFB;
            --text-muted: #9CA3AF;
            --text-sub: #64748B;
        }
        body {
            background-color: var(--bg-main);
            color: var(--text-high);
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
            overflow-x: hidden;
            scroll-behavior: smooth;
        }
        .glass-card {
            background: var(--bg-card);
            backdrop-filter: blur(16px);
            -webkit-backdrop-filter: blur(16px);
            border: 1px solid var(--border-glow);
            box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
        }
        .glass-card-hover {
            transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
        }
        .glass-card-hover:hover {
            transform: translateY(-4px);
            border-color: rgba(56, 189, 248, 0.45);
            box-shadow: 0 14px 38px rgba(37, 99, 235, 0.25);
        }
        .btn-glow {
            background: linear-gradient(135deg, #38BDF8 0%, #2563EB 100%);
            box-shadow: 0 0 24px rgba(56, 189, 248, 0.4);
            transition: all 0.3s ease;
        }
        .btn-glow:hover {
            box-shadow: 0 0 32px rgba(56, 189, 248, 0.65);
            transform: translateY(-2px);
        }
        .btn-outline {
            border: 1px solid rgba(56, 189, 248, 0.4);
            background: rgba(15, 23, 42, 0.6);
            backdrop-filter: blur(8px);
            transition: all 0.3s ease;
        }
        .btn-outline:hover {
            background: rgba(56, 189, 248, 0.15);
            border-color: #38BDF8;
        }
        .text-gradient {
            background: linear-gradient(135deg, #FFFFFF 30%, #38BDF8 100%);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
        }
        .text-gradient-sub {
            background: linear-gradient(135deg, #38BDF8 0%, #818CF8 100%);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
        }
        details > summary {
            list-style: none;
        }
        details > summary::-webkit-details-marker {
            display: none;
        }
        details[open] summary svg {
            transform: rotate(180deg);
        }
        .slide-fade {
            display: none;
            opacity: 0;
            transition: opacity 0.6s ease-in-out;
        }
        .slide-fade.active {
            display: block;
            opacity: 1;
        }
        .code-syntax {
            font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
        }
        .fixed-bottom-bar {
            background: rgba(11, 15, 25, 0.92);
            backdrop-filter: blur(12px);
            border-top: 1px solid rgba(56, 189, 248, 0.25);
        }