/* roulang page: index */
:root {
            --color-primary: #1E40AF;
            --color-primary-hover: #1D4ED8;
            --color-accent: #0EA5E9;
            --color-success: #10B981;
            --color-bg-main: #F8FAFC;
            --color-bg-card: #FFFFFF;
            --color-bg-dark: #0F172A;
            --color-text-main: #0F172A;
            --color-text-muted: #475569;
            --color-text-light: #94A3B8;
            --color-border: rgba(226, 232, 240, 0.85);
            --radius-lg: 1rem;
            --radius-xl: 1.25rem;
            --transition-base: all 0.28s cubic-bezier(0.16, 1, 0.3, 1);
        }

        *, *::before, *::after {
            box-sizing: border-box;
        }

        body {
            font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
            background-color: var(--color-bg-main);
            color: var(--color-text-main);
            line-height: 1.65;
            overflow-x: hidden;
            margin: 0;
            -webkit-font-smoothing: antialiased;
        }

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

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

        /* Layout & Container */
        .site-container {
            width: 100%;
            max-width: 1280px;
            margin-left: auto;
            margin-right: auto;
            padding-left: 1.25rem;
            padding-right: 1.25rem;
        }

        @media (min-width: 768px) {
            .site-container {
                padding-left: 2rem;
                padding-right: 2rem;
            }
        }

        .section-block {
            padding-top: 5rem;
            padding-bottom: 5rem;
            position: relative;
        }

        @media (max-width: 767px) {
            .section-block {
                padding-top: 3.5rem;
                padding-bottom: 3.5rem;
            }
        }

        /* Promo Topbar & Sticky Nav */
        .promo-topbar {
            background-color: var(--color-bg-dark);
            color: #E2E8F0;
            font-size: 0.8125rem;
            border-bottom: 1px solid rgba(255, 255, 255, 0.08);
        }

        .main-header {
            position: sticky;
            top: 0;
            z-index: 50;
            background: rgba(255, 255, 255, 0.92);
            backdrop-filter: blur(12px);
            -webkit-backdrop-filter: blur(12px);
            border-bottom: 1px solid var(--color-border);
            box-shadow: 0 4px 20px -4px rgba(15, 23, 42, 0.04);
        }

        .nav-link {
            position: relative;
            font-weight: 500;
            color: #334155;
            padding: 0.5rem 0.75rem;
            border-radius: 0.5rem;
            font-size: 0.9375rem;
        }

        .nav-link:hover, .nav-link.active {
            color: var(--color-primary);
            background-color: rgba(30, 64, 175, 0.05);
        }

        .nav-link.active::after {
            content: '';
            position: absolute;
            bottom: 2px;
            left: 0.75rem;
            right: 0.75rem;
            height: 2px;
            background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
            border-radius: 2px;
        }

        /* Cards & Interactive Surfaces */
        .surface-card {
            background-color: var(--color-bg-card);
            border: 1px solid var(--color-border);
            border-radius: var(--radius-lg);
            box-shadow: 0 2px 10px -2px rgba(15, 23, 42, 0.05);
            transition: var(--transition-base);
        }

        .surface-card:hover {
            transform: translateY(-4px);
            box-shadow: 0 20px 25px -5px rgba(30, 64, 175, 0.10), 0 8px 10px -6px rgba(30, 64, 175, 0.06);
            border-color: rgba(14, 165, 233, 0.45);
        }

        /* Buttons */
        .btn-primary {
            display: inline-flex;
            align-items: center;
            justify-content: center;
            gap: 0.5rem;
            background: linear-gradient(135deg, #1E40AF 0%, #2563EB 100%);
            color: #FFFFFF;
            font-weight: 600;
            padding: 0.75rem 1.5rem;
            border-radius: 0.625rem;
            box-shadow: 0 4px 12px rgba(30, 64, 175, 0.25);
            transition: var(--transition-base);
            min-height: 44px;
            border: none;
            cursor: pointer;
        }

        .btn-primary:hover {
            background: linear-gradient(135deg, #1E3A8A 0%, #1D4ED8 100%);
            transform: translateY(-2px);
            box-shadow: 0 8px 20px rgba(30, 64, 175, 0.35);
        }

        .btn-outline {
            display: inline-flex;
            align-items: center;
            justify-content: center;
            gap: 0.5rem;
            background-color: #FFFFFF;
            color: var(--color-primary);
            border: 1.5px solid rgba(30, 64, 175, 0.25);
            font-weight: 600;
            padding: 0.75rem 1.5rem;
            border-radius: 0.625rem;
            transition: var(--transition-base);
            min-height: 44px;
            cursor: pointer;
        }

        .btn-outline:hover {
            border-color: var(--color-primary);
            background-color: #EFF6FF;
            transform: translateY(-2px);
        }

        /* Magazine Hero Split Grid */
        .hero-magazine-grid {
            display: grid;
            grid-template-columns: 1fr;
            gap: 2.5rem;
            align-items: stretch;
        }

        @media (min-width: 1024px) {
            .hero-magazine-grid {
                grid-template-columns: 7fr 5fr;
                gap: 3rem;
            }
        }

        /* Code & Topology Block */
        .code-window {
            background: #090E1A;
            border: 1px solid rgba(56, 189, 248, 0.2);
            border-radius: 0.875rem;
            font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
        }

        /* Custom Scrollbar for horizontal strips */
        .no-scrollbar::-webkit-scrollbar {
            display: none;
        }
        .no-scrollbar {
            -ms-overflow-style: none;
            scrollbar-width: none;
        }

        /* FAQ Accordion Transition */
        .faq-answer {
            max-height: 0;
            overflow: hidden;
            transition: max-height 0.32s ease-out, padding 0.25s ease;
        }
        .faq-item.open .faq-answer {
            max-height: 360px;
        }
        .faq-item.open .faq-icon {
            transform: rotate(180deg);
        }

        /* Sticky Bottom Bar */
        #stickyBottomBar {
            transform: translateY(120%);
            transition: transform 0.35s cubic-bezier(0.16, 1, 0.3, 1);
        }
        #stickyBottomBar.visible {
            transform: translateY(0);
        }