/* roulang page: index */
/* design tokens & reset */
        :root {
            --deep-navy: #0A1128;
            --midnight-blue: #0F1B3D;
            --glacier-blue: #00E5FF;
            --electric-purple: #7B2FFF;
            --steel-blue: #B0C4DE;
            --light-gray: #AAB8C2;
            --glass-bg: rgba(255,255,255,0.05);
            --glass-border: rgba(255,255,255,0.1);
            --card-radius: 16px;
            --btn-radius: 30px;
            --glow-shadow: 0 0 20px rgba(0,229,255,0.6);
            --section-gap: 90px;
            --font-sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
            --transition-smooth: 0.25s cubic-bezier(0.2, 0.0, 0, 1.0);
        }

        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
        }

        body {
            font-family: var(--font-sans);
            background: linear-gradient(160deg, #0A1128 0%, #0F1B3D 100%);
            color: #E5ECF4;
            line-height: 1.7;
            font-size: 16px;
            -webkit-font-smoothing: antialiased;
        }

        a {
            text-decoration: none;
            color: inherit;
            transition: var(--transition-smooth);
        }

        img {
            max-width: 100%;
            height: auto;
            display: block;
        }

        .container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 24px;
        }

        /* typography */
        h1 { font-size: 48px; font-weight: 700; letter-spacing: -0.5px; }
        h2 { font-size: 36px; font-weight: 600; margin-bottom: 20px; }
        h3 { font-size: 22px; font-weight: 600; }
        h4 { font-size: 18px; font-weight: 600; }
        p { color: var(--steel-blue); margin-bottom: 16px; }

        /* glass card */
        .glass-card {
            background: rgba(255,255,255,0.03);
            backdrop-filter: blur(20px);
            -webkit-backdrop-filter: blur(20px);
            border: 1px solid rgba(255,255,255,0.08);
            border-radius: var(--card-radius);
            box-shadow: 0 12px 32px rgba(0,229,255,0.05);
            transition: all 0.3s ease;
        }

        /* navigation */
        .top-bar {
            background: transparent;
            position: fixed;
            width: 100%;
            top: 0;
            z-index: 99;
            height: 72px;
            padding: 0 24px;
            transition: background 0.3s, backdrop-filter 0.3s;
        }
        .top-bar.scrolled {
            background: rgba(10,17,40,0.85);
            backdrop-filter: blur(20px);
            -webkit-backdrop-filter: blur(20px);
            border-bottom: 1px solid rgba(255,255,255,0.08);
        }
        .nav-container {
            display: flex;
            align-items: center;
            justify-content: space-between;
            height: 100%;
            max-width: 1300px;
            margin: 0 auto;
        }
        .logo {
            font-weight: 700;
            font-size: 24px;
            letter-spacing: 1px;
            color: #fff;
            background: linear-gradient(135deg, #00E5FF, #7B2FFF);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
        }
        .nav-links {
            display: flex;
            align-items: center;
            gap: 28px;
            list-style: none;
        }
        .nav-links li a {
            color: #D0DBEA;
            font-weight: 500;
            font-size: 15px;
            position: relative;
            padding: 8px 0;
        }
        .nav-links li a::after {
            content: '';
            position: absolute;
            bottom: 0;
            left: 0;
            width: 0;
            height: 2px;
            background: var(--glacier-blue);
            transition: width 0.3s;
        }
        .nav-links li a:hover::after,
        .nav-links li a.active::after { width: 100%; }
        .nav-links li a:hover { color: #fff; }
        .nav-divider {
            width: 1px;
            height: 18px;
            background: rgba(255,255,255,0.25);
            margin: 0 2px;
        }
        .menu-icon {
            display: none;
            flex-direction: column;
            gap: 5px;
            cursor: pointer;
        }
        .menu-icon span {
            width: 24px;
            height: 2px;
            background: #fff;
            border-radius: 2px;
        }

        /* buttons */
        .btn {
            font-weight: 600;
            padding: 14px 32px;
            border-radius: var(--btn-radius);
            display: inline-block;
            text-align: center;
            font-size: 16px;
            transition: all 0.3s;
        }
        .btn-primary {
            background: linear-gradient(135deg, #00E5FF, #00B4D8);
            color: #0A1128;
            box-shadow: 0 8px 18px rgba(0,229,255,0.3);
        }
        .btn-primary:hover {
            box-shadow: 0 0 28px rgba(0,229,255,0.7);
            transform: scale(1.03);
            color: #0A1128;
        }
        .btn-ghost {
            border: 1px solid var(--glacier-blue);
            color: var(--glacier-blue);
            background: transparent;
        }
        .btn-ghost:hover {
            background: rgba(0,229,255,0.1);
            border-color: #fff;
            color: #fff;
        }

        /* hero */
        .hero-section {
            padding-top: 140px;
            padding-bottom: 100px;
            display: flex;
            align-items: center;
            gap: 60px;
        }
        .hero-left { flex: 0 0 58%; }
        .hero-right { flex: 0 0 38%; }
        .hero-title {
            background: linear-gradient(to right, #FFFFFF, #B0E0FF);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
        }
        .hero-sub {
            font-size: 18px;
            color: #A1B5D0;
            margin: 24px 0 32px;
        }
        .hero-img {
            border-radius: 24px;
            border: 1px solid rgba(0,229,255,0.25);
            box-shadow: 0 20px 40px rgba(0,229,255,0.15);
            background: #0B152D;
        }

        /* highlights grid */
        .highlights-grid {
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            gap: 30px;
            margin-top: 40px;
        }
        .highlight-card {
            padding: 32px 24px;
            text-align: left;
            transition: all 0.3s;
        }
        .highlight-card i {
            font-size: 32px;
            color: var(--glacier-blue);
            margin-bottom: 18px;
        }
        .highlight-card:hover {
            border-color: rgba(0,229,255,0.5);
            transform: translateY(-6px);
            box-shadow: 0 18px 40px rgba(0,229,255,0.12);
        }

        /* waterfall cases */
        .waterfall-grid {
            column-count: 3;
            column-gap: 28px;
            margin-top: 40px;
        }
        .case-item {
            break-inside: avoid;
            margin-bottom: 28px;
            background: rgba(255,255,255,0.03);
            backdrop-filter: blur(16px);
            border-radius: 18px;
            overflow: hidden;
            border:1px solid rgba(255,255,255,0.07);
            transition: 0.3s;
        }
        .case-item img {
            transition: transform 0.4s;
        }
        .case-item:hover img { transform: scale(1.04); }
        .case-content {
            padding: 20px;
        }
        .tag {
            background: rgba(0,229,255,0.15);
            color: #00E5FF;
            padding: 4px 12px;
            border-radius: 20px;
            font-size: 12px;
            font-weight: 600;
        }

        /* pricing */
        .pricing-grid {
            display: flex;
            gap: 30px;
            justify-content: center;
            flex-wrap: wrap;
        }
        .pricing-card {
            flex: 1 1 280px;
            padding: 40px 28px;
            position: relative;
        }
        .pricing-card.popular {
            border: 1px solid var(--electric-purple);
            box-shadow: 0 0 28px rgba(123,47,255,0.3);
        }
        .badge-hot {
            position: absolute;
            top: -14px;
            right: 20px;
            background: #7B2FFF;
            color: white;
            padding: 6px 18px;
            border-radius: 20px;
            font-weight: bold;
            font-size: 13px;
        }

        /* FAQ */
        .faq-item {
            background: rgba(255,255,255,0.04);
            border-radius: 14px;
            margin-bottom: 16px;
            padding: 18px 24px;
            cursor: pointer;
        }
        .faq-question {
            display: flex;
            justify-content: space-between;
            font-weight: 600;
        }

        /* cta banner */
        .cta-global {
            background: radial-gradient(circle at 30% 30%, #1A234E, #0A1128);
            border: 1px solid rgba(0,229,255,0.15);
            border-radius: 32px;
            padding: 70px 30px;
            text-align: center;
        }

        /* footer */
        .footer-grid {
            display: grid;
            grid-template-columns: 2fr 1fr 2fr 1fr;
            gap: 40px;
        }

        @media (max-width: 1024px) {
            h1 { font-size: 38px; }
            .waterfall-grid { column-count: 2; }
            .footer-grid { grid-template-columns: 1fr 1fr; }
        }

        @media (max-width: 768px) {
            .hero-section { flex-direction: column; }
            .highlights-grid { grid-template-columns: 1fr; }
            .waterfall-grid { column-count: 1; }
            .nav-links { display: none; }
            .menu-icon { display: flex; }
            .pricing-grid { flex-direction: column; }
        }