/* roulang page: index */
@import url('https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.4.0/css/all.min.css');

        :root {
            --color-primary: #4F46E5;
            --color-primary-deep: #3730A3;
            --color-cyan-bright: #06B6D4;
            --color-sun: #F59E0B;
            --color-sun-deep: #D97706;
            --color-bg: #F6F7F9;
            --color-card: #FFFFFF;
            --color-ink-strong: #0F172A;
            --color-ink-body: #334155;
            --color-ink-weak: #94A3B8;
            --color-night: #0B1120;
            --brand-gradient: linear-gradient(135deg, #4F46E5 0%, #06B6D4 55%, #F59E0B 130%);
            --hero-gradient: linear-gradient(140deg, #0F172A 0%, #1E1B4B 40%, #0E7490 100%);
        }

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

        html {
            scroll-behavior: smooth;
        }

        body {
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
            background-color: var(--color-bg);
            color: var(--color-ink-body);
            line-height: 1.75;
            -webkit-font-smoothing: antialiased;
            -moz-osx-font-smoothing: grayscale;
        }

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

        a {
            text-decoration: none;
            color: inherit;
            transition: color 0.2s ease;
        }

        a:focus-visible,
        button:focus-visible,
        input:focus-visible {
            outline: 3px solid rgba(79, 70, 229, 0.4);
            outline-offset: 2px;
            border-radius: 4px;
        }

        .container-site {
            max-width: 1180px;
            margin: 0 auto;
            padding: 0 1rem;
        }

        @media (min-width: 640px) {
            .container-site {
                padding: 0 1.25rem;
            }
        }

        @media (min-width: 768px) {
            .container-site {
                padding: 0 1.5rem;
            }
        }

        @media (min-width: 1024px) {
            .container-site {
                padding: 0 2rem;
            }
        }

        .btn-primary {
            display: inline-flex;
            align-items: center;
            justify-content: center;
            gap: 0.5rem;
            padding: 0.75rem 1.75rem;
            background: var(--color-sun);
            color: #fff;
            font-weight: 600;
            font-size: 0.9375rem;
            border-radius: 0.75rem;
            border: 2px solid transparent;
            cursor: pointer;
            transition: all 0.25s ease;
            box-shadow: 0 4px 12px rgba(245, 158, 11, 0.3);
        }

        .btn-primary:hover {
            background: var(--color-sun-deep);
            transform: translateY(-2px);
            box-shadow: 0 6px 18px rgba(217, 119, 6, 0.4);
        }

        .btn-primary:active {
            transform: translateY(0);
        }

        .btn-ghost {
            display: inline-flex;
            align-items: center;
            justify-content: center;
            gap: 0.5rem;
            padding: 0.75rem 1.75rem;
            background: transparent;
            color: #fff;
            font-weight: 600;
            font-size: 0.9375rem;
            border-radius: 0.75rem;
            border: 1.5px solid rgba(255, 255, 255, 0.6);
            cursor: pointer;
            transition: all 0.25s ease;
        }

        .btn-ghost:hover {
            background: rgba(255, 255, 255, 0.1);
            border-color: #fff;
        }

        .btn-ghost-dark {
            display: inline-flex;
            align-items: center;
            justify-content: center;
            gap: 0.5rem;
            padding: 0.75rem 1.75rem;
            background: white;
            color: var(--color-primary);
            font-weight: 600;
            font-size: 0.9375rem;
            border-radius: 0.75rem;
            border: 1.5px solid rgba(79, 70, 229, 0.2);
            cursor: pointer;
            transition: all 0.25s ease;
        }

        .btn-ghost-dark:hover {
            background: var(--color-brand-light);
            border-color: var(--color-primary);
            transform: translateY(-2px);
        }

        .card-base {
            background: var(--color-card);
            border: 1px solid rgba(15, 23, 42, 0.06);
            border-radius: 1.5rem;
            box-shadow: 0 1px 3px rgba(15, 23, 42, 0.06), 0 8px 24px rgba(15, 23, 42, 0.08);
            transition: all 0.3s ease;
        }

        .card-base:hover {
            box-shadow: 0 2px 6px rgba(15, 23, 42, 0.08), 0 18px 40px rgba(15, 23, 42, 0.12);
        }

        .input-base {
            width: 100%;
            height: 3rem;
            border: 1px solid #E2E8F0;
            border-radius: 0.75rem;
            padding: 0 1rem;
            font-size: 0.9375rem;
            background: #fff;
            transition: all 0.25s ease;
        }

        .input-base:focus {
            border-color: var(--color-primary);
            box-shadow: 0 0 0 4px rgba(79, 70, 229, 0.1);
            outline: none;
        }

        .gradient-bar {
            height: 4px;
            background: var(--brand-gradient);
            border: none;
        }

        .text-gradient-brand {
            background: var(--brand-gradient);
            -webkit-background-clip: text;
            background-clip: text;
            -webkit-text-fill-color: transparent;
            color: transparent;
        }

        .hero-bg {
            background: var(--hero-gradient);
            position: relative;
            overflow: hidden;
        }

        .hero-bg::before {
            content: '';
            position: absolute;
            inset: 0;
            background-image: url('/assets/images/backpic/back-1.webp');
            background-size: cover;
            background-position: center;
            opacity: 0.18;
            z-index: 0;
        }

        .hero-bg::after {
            content: '';
            position: absolute;
            inset: 0;
            background: linear-gradient(140deg, rgba(15,23,42,0.9) 0%, rgba(30,27,75,0.7) 40%, rgba(14,116,144,0.5) 100%);
            z-index: 1;
        }

        .light-beam {
            position: absolute;
            top: -30%;
            width: 120px;
            height: 160%;
            background: linear-gradient(90deg, transparent, rgba(255,255,255,0.12), transparent);
            transform: rotate(25deg);
            z-index: 2;
            animation: beamMove 8s ease-in-out infinite alternate;
        }

        .light-beam.lb-left {
            left: 10%;
        }

        .light-beam.lb-right {
            left: 55%;
            animation-delay: 3s;
            background: linear-gradient(90deg, transparent, rgba(245,158,11,0.08), transparent);
        }

        @keyframes beamMove {
            0% {
                transform: rotate(25deg) translateX(-20px);
            }
            100% {
                transform: rotate(25deg) translateX(80px);
            }
        }

        .hero-content {
            position: relative;
            z-index: 3;
        }

        .stat-number {
            font-size: clamp(1.75rem, 3vw, 2.5rem);
            font-weight: 800;
            font-variant-numeric: tabular-nums;
            letter-spacing: -0.01em;
        }

        .step-number {
            font-size: 3.5rem;
            font-weight: 800;
            line-height: 1;
            background: var(--brand-gradient);
            -webkit-background-clip: text;
            background-clip: text;
            -webkit-text-fill-color: transparent;
            color: transparent;
            opacity: 0.85;
        }

        .list-marker-brand {
            list-style: none;
            padding-left: 0;
        }

        .list-marker-brand li {
            position: relative;
            padding-left: 1.5rem;
            margin-bottom: 0.5rem;
        }

        .list-marker-brand li::before {
            content: '';
            position: absolute;
            left: 0;
            top: 0.6em;
            width: 8px;
            height: 8px;
            border-radius: 2px;
            background: var(--color-primary);
        }

        .nav-split {
            transition: all 0.3s ease;
        }

        .nav-split.scrolled {
            background: rgba(255, 255, 255, 0.92);
            backdrop-filter: blur(12px);
            -webkit-backdrop-filter: blur(12px);
            box-shadow: 0 1px 6px rgba(15, 23, 42, 0.08);
        }

        .nav-split.scrolled .nav-link-light {
            color: var(--color-ink-strong);
        }

        .nav-split.scrolled .nav-logo-text {
            color: var(--color-ink-strong);
        }

        .nav-link-light {
            color: rgba(255, 255, 255, 0.85);
            font-weight: 500;
            font-size: 0.9375rem;
            padding: 0.5rem 0.25rem;
            border-bottom: 2px solid transparent;
            transition: all 0.25s ease;
        }

        .nav-link-light:hover {
            color: #fff;
        }

        .nav-link-light.active {
            color: #fff;
            border-bottom-color: var(--color-sun);
        }

        .nav-split.scrolled .nav-link-light:hover {
            color: var(--color-primary);
        }

        .nav-split.scrolled .nav-link-light.active {
            color: var(--color-primary);
            border-bottom-color: var(--color-primary);
        }

        .faq-item .faq-answer {
            max-height: 0;
            overflow: hidden;
            opacity: 0;
            transition: max-height 0.4s ease, opacity 0.3s ease;
        }

        .faq-item.open .faq-answer {
            max-height: 500px;
            opacity: 1;
        }

        .faq-item.open .faq-icon {
            transform: rotate(45deg);
            background: var(--color-primary);
            color: #fff;
        }

        .faq-icon {
            width: 32px;
            height: 32px;
            border-radius: 10px;
            display: inline-flex;
            align-items: center;
            justify-content: center;
            font-size: 1.25rem;
            font-weight: 600;
            background: #F1F5F9;
            color: var(--color-primary);
            transition: all 0.3s ease;
            flex-shrink: 0;
        }

        .qr-code-sim {
            width: 96px;
            height: 96px;
            border-radius: 1rem;
            background: linear-gradient(135deg, #1E1B4B, #0E7490);
            position: relative;
            overflow: hidden;
            padding: 10px;
        }

        .qr-code-sim::before {
            content: '';
            position: absolute;
            inset: 12px;
            background: repeating-linear-gradient(0deg, transparent 0px, transparent 4px, #e2e8f0 4px, #e2e8f0 6px);
            opacity: 0.9;
            border-radius: 4px;
        }

        .qr-code-sim::after {
            content: '';
            position: absolute;
            width: 24px;
            height: 24px;
            background: #0F172A;
            border-radius: 4px;
            top: 14px;
            left: 14px;
            box-shadow: 40px 0 0 #0F172A, 0 40px 0 #0F172A, 40px 40px 0 #0F172A;
        }

        .toc-link {
            display: block;
            padding: 0.5rem 0.75rem;
            border-radius: 0.5rem;
            font-size: 0.9rem;
            color: var(--color-ink-body);
            transition: all 0.2s ease;
            border-left: 3px solid transparent;
        }

        .toc-link:hover {
            background: #F1F5F9;
            color: var(--color-primary);
        }

        .toc-link.active {
            background: var(--color-brand-light);
            color: var(--color-primary);
            font-weight: 600;
            border-left-color: var(--color-primary);
        }

        .animate-fade-up {
            opacity: 0;
            transform: translateY(30px);
            transition: opacity 0.8s ease, transform 0.8s ease;
        }

        .animate-fade-up.visible {
            opacity: 1;
            transform: translateY(0);
        }

        .section-icon-block {
            width: 48px;
            height: 48px;
            border-radius: 14px;
            background: var(--brand-gradient);
            display: inline-flex;
            align-items: center;
            justify-content: center;
            color: #fff;
            font-size: 1.25rem;
            flex-shrink: 0;
        }

        .mobile-nav {
            display: none;
        }

        .mobile-nav.open {
            display: block;
        }

        @media (max-width: 767px) {
            .desktop-nav {
                display: none !important;
            }
            .mobile-nav {
                display: block;
            }
            .mobile-nav.open {
                display: flex;
                flex-direction: column;
                position: fixed;
                inset: 0;
                background: rgba(255, 255, 255, 0.98);
                backdrop-filter: blur(16px);
                z-index: 100;
                padding: 5rem 2rem 2rem;
            }
            .mobile-nav-link {
                font-size: 1.125rem;
                font-weight: 600;
                color: var(--color-ink-strong);
                padding: 1rem 0;
                border-bottom: 1px solid #F1F5F9;
            }
        }

/* roulang page: article */
@layer base {
            :root {
                --color-primary: #4F46E5;
                --color-primary-deep: #3730A3;
                --color-cyan-bright: #06B6D4;
                --color-sun: #F59E0B;
                --color-sun-deep: #D97706;
                --color-bg: #F6F7F9;
                --color-card: #FFFFFF;
                --color-ink-strong: #0F172A;
                --color-ink-body: #334155;
                --color-ink-weak: #94A3B8;
                --color-night: #0B1120;
                --brand-gradient: linear-gradient(135deg, #4F46E5 0%, #06B6D4 55%, #F59E0B 130%);
                --hero-gradient: linear-gradient(140deg, #0F172A 0%, #1E1B4F 40%, #0E7490 100%);
            }

            body {
                font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
                background-color: var(--color-bg);
                color: var(--color-ink-body);
                line-height: 1.75;
                -webkit-font-smoothing: antialiased;
            }

            .container-site {
                max-width: 1180px;
                margin: 0 auto;
                padding-left: 1rem;
                padding-right: 1rem;
            }

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

            a {
                color: inherit;
                text-decoration: none;
            }
            img { max-width: 100%; height: auto; }
        }

        @layer components {
            .btn-primary {
                @apply inline-flex items-center justify-center gap-2 px-5 py-3 rounded-xl font-semibold text-white transition-all duration-300;
                background-color: var(--color-sun);
            }
            .btn-primary:hover {
                background-color: var(--color-sun-deep);
                transform: translateY(-2px);
                box-shadow: 0 8px 24px rgba(245, 158, 11, 0.3);
            }
            .btn-outline {
                @apply inline-flex items-center justify-center gap-2 px-5 py-3 rounded-xl font-semibold border transition-all duration-300;
                border-color: rgba(255,255,255,0.6);
                color: #fff;
            }
            .btn-outline:hover {
                background-color: rgba(255,255,255,0.1);
                border-color: rgba(255,255,255,0.95);
            }
            .card-base {
                @apply bg-white rounded-2xl border;
                border-color: rgba(15,23,42,0.06);
                box-shadow: 0 1px 3px rgba(15,23,42,0.06), 0 8px 24px rgba(15,23,42,0.08);
            }
            .gradient-bar {
                height: 4px;
                background: var(--brand-gradient);
            }
            .nav-link-light {
                @apply text-[0.95rem] font-medium text-white/85 transition-colors duration-200;
            }
            .nav-link-light:hover {
                color: #ffffff;
            }
            .nav-link-light.active {
                color: #ffffff;
                position: relative;
            }
            .nav-link-light.active::after {
                content: '';
                position: absolute;
                left: 0.25rem;
                right: 0.25rem;
                bottom: -0.4rem;
                height: 3px;
                border-radius: 9999px;
                background: var(--brand-gradient);
            }
        }

        /* -------- 导航滚动状态 -------- */
        .nav-split {
            transition: background-color 0.35s ease, box-shadow 0.35s ease;
            background-color: transparent;
        }
        .nav-split.scrolled {
            background-color: rgba(255,255,255,0.92);
            backdrop-filter: blur(14px);
            -webkit-backdrop-filter: blur(14px);
            box-shadow: 0 2px 12px rgba(15,23,42,0.08);
        }
        .nav-split.scrolled .nav-logo-text {
            color: var(--color-ink-strong);
        }
        .nav-split.scrolled .nav-link-light {
            color: var(--color-ink-body);
        }
        .nav-split.scrolled .nav-link-light:hover {
            color: var(--color-primary);
        }
        .nav-split.scrolled .nav-link-light.active {
            color: var(--color-primary);
        }
        .nav-split.scrolled .nav-link-light.active::after {
            background: var(--brand-gradient);
        }
        .nav-split.scrolled .nav-search-btn {
            color: var(--color-ink-body);
        }
        .nav-split.scrolled .nav-search-btn:hover {
            color: var(--color-primary);
        }
        .nav-split.scrolled .nav-burger {
            color: var(--color-ink-strong);
        }
        .nav-logo-text {
            transition: color 0.35s ease;
        }

        /* -------- 文章正文排版 -------- */
        .article-content {
            font-size: 1rem;
            line-height: 1.85;
            color: var(--color-ink-body);
            word-break: break-word;
        }
        .article-content p {
            margin-bottom: 1.25rem;
        }
        .article-content h2 {
            font-size: 1.5rem;
            font-weight: 700;
            color: var(--color-ink-strong);
            margin-top: 2.5rem;
            margin-bottom: 1rem;
            padding-left: 0.9rem;
            border-left: 4px solid var(--color-primary);
            line-height: 1.35;
        }
        .article-content h3 {
            font-size: 1.25rem;
            font-weight: 600;
            color: var(--color-ink-strong);
            margin-top: 2rem;
            margin-bottom: 0.75rem;
        }
        .article-content h4 {
            font-size: 1.075rem;
            font-weight: 600;
            color: var(--color-ink-strong);
            margin-top: 1.5rem;
            margin-bottom: 0.5rem;
        }
        .article-content img {
            border-radius: 1rem;
            box-shadow: 0 4px 16px rgba(15,23,42,0.10);
            margin: 1.5rem auto;
        }
        .article-content blockquote {
            border-left: 4px solid var(--color-sun);
            background: #FFFBEB;
            padding: 1rem 1.25rem;
            border-radius: 0.75rem;
            margin: 1.5rem 0;
            color: var(--color-ink-body);
        }
        .article-content ul {
            list-style: none;
            padding-left: 0;
            margin: 1rem 0;
        }
        .article-content ul li {
            position: relative;
            padding-left: 1.6rem;
            margin-bottom: 0.5rem;
        }
        .article-content ul li::before {
            content: '';
            position: absolute;
            left: 0.1rem;
            top: 0.65em;
            width: 8px;
            height: 8px;
            border-radius: 3px;
            background: var(--brand-gradient);
        }
        .article-content ol {
            list-style: none;
            padding-left: 0;
            counter-reset: article-ol;
            margin: 1rem 0;
        }
        .article-content ol li {
            position: relative;
            padding-left: 2rem;
            margin-bottom: 0.5rem;
            counter-increment: article-ol;
        }
        .article-content ol li::before {
            content: counter(article-ol) ".";
            position: absolute;
            left: 0.35rem;
            font-weight: 700;
            color: var(--color-primary);
        }
        .article-content a {
            color: var(--color-primary);
            text-decoration: underline;
            text-underline-offset: 3px;
            transition: color 0.2s ease;
        }
        .article-content a:hover {
            color: var(--color-primary-deep);
        }
        .article-content code {
            background: #F1F5F9;
            padding: 0.2em 0.45em;
            border-radius: 0.375rem;
            font-size: 0.9em;
            font-family: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
        }
        .article-content pre {
            background: #0F172A;
            color: #E2E8F0;
            padding: 1.25rem;
            border-radius: 1rem;
            overflow-x: auto;
            margin: 1.5rem 0;
            font-size: 0.9rem;
            line-height: 1.7;
        }
        .article-content table {
            width: 100%;
            border-collapse: collapse;
            margin: 1.5rem 0;
            font-size: 0.95rem;
        }
        .article-content th,
        .article-content td {
            border: 1px solid #E2E8F0;
            padding: 0.75rem 1rem;
            text-align: left;
        }
        .article-content th {
            background: #F8FAFC;
            font-weight: 600;
            color: var(--color-ink-strong);
        }
        .article-content hr {
            border: 0;
            height: 1px;
            background: #E2E8F0;
            margin: 2rem 0;
        }

/* roulang page: category1 */
:root {
            --color-primary: #4F46E5;
            --color-primary-deep: #3730A3;
            --color-cyan-bright: #06B6D4;
            --color-sun: #F59E0B;
            --color-sun-deep: #D97706;
            --color-bg: #F6F7F9;
            --color-card: #FFFFFF;
            --color-ink-strong: #0F172A;
            --color-ink-body: #334155;
            --color-ink-weak: #94A3B8;
            --color-night: #0B1120;
            --brand-gradient: linear-gradient(135deg, #4F46E5 0%, #06B6D4 55%, #F59E0B 130%);
            --hero-gradient: linear-gradient(140deg, #0F172A 0%, #1E1B4B 40%, #0E7490 100%);
            --card-shadow: 0 1px 3px rgba(15,23,42,0.06), 0 8px 24px rgba(15,23,42,0.08);
            --card-shadow-hover: 0 2px 6px rgba(15,23,42,0.08), 0 18px 40px rgba(15,23,42,0.12);
        }
        * { box-sizing: border-box; margin: 0; padding: 0; }
        html { scroll-behavior: smooth; }
        body {
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
            color: var(--color-ink-body);
            background-color: var(--color-bg);
            line-height: 1.75;
        }
        a { text-decoration: none; color: inherit; }
        img { max-width: 100%; display: block; }
        button { cursor: pointer; background: none; border: none; }

        @layer components {
            .container-site {
                max-width: 1180px;
                margin-left: auto;
                margin-right: auto;
                padding-left: 1.25rem;
                padding-right: 1.25rem;
            }
            .btn-primary {
                display: inline-flex;
                align-items: center;
                justify-content: center;
                gap: 0.375rem;
                background-color: var(--color-sun);
                color: #fff;
                font-weight: 600;
                border-radius: 0.75rem;
                padding: 0.625rem 1.25rem;
                transition: all 0.25s ease;
                box-shadow: 0 2px 8px rgba(245,158,11,0.25);
            }
            .btn-primary:hover {
                background-color: var(--color-sun-deep);
                transform: translateY(-2px);
                box-shadow: 0 4px 16px rgba(245,158,11,0.35);
            }
            .btn-ghost {
                display: inline-flex;
                align-items: center;
                justify-content: center;
                gap: 0.375rem;
                border: 1px solid rgba(255,255,255,0.4);
                color: #fff;
                font-weight: 600;
                border-radius: 0.75rem;
                padding: 0.625rem 1.25rem;
                transition: all 0.25s ease;
            }
            .btn-ghost:hover { background-color: rgba(255,255,255,0.1); }
            .btn-outline {
                display: inline-flex;
                align-items: center;
                justify-content: center;
                gap: 0.375rem;
                border: 1px solid #E2E8F0;
                color: var(--color-ink-strong);
                font-weight: 600;
                border-radius: 0.75rem;
                padding: 0.625rem 1.25rem;
                background: #fff;
                transition: all 0.25s ease;
            }
            .btn-outline:hover {
                border-color: var(--color-primary);
                color: var(--color-primary);
                background: rgba(79,70,229,0.04);
            }
            .card-base {
                background-color: var(--color-card);
                border-radius: 1.5rem;
                border: 1px solid rgba(15,23,42,0.06);
                box-shadow: var(--card-shadow);
                transition: box-shadow 0.3s ease, transform 0.3s ease;
            }
            .card-base:hover {
                box-shadow: var(--card-shadow-hover);
            }
            .gradient-bar { height: 4px; background: var(--brand-gradient); }
            .input-base {
                width: 100%;
                height: 2.75rem;
                border-radius: 0.75rem;
                border: 1px solid #E2E8F0;
                padding: 0 0.875rem;
                font-size: 0.875rem;
                background: #fff;
                color: var(--color-ink-strong);
                transition: border-color 0.2s, box-shadow 0.2s;
            }
            .input-base:focus {
                outline: none;
                border-color: var(--color-primary);
                box-shadow: 0 0 0 4px rgba(79,70,229,0.1);
            }
        }

        /* 导航 */
        .nav-split {
            transition: background-color 0.35s ease, box-shadow 0.35s ease, backdrop-filter 0.35s ease;
        }
        .nav-split.scrolled {
            background-color: rgba(255,255,255,0.92);
            backdrop-filter: blur(12px);
            box-shadow: 0 1px 10px rgba(15,23,42,0.08);
        }
        .nav-split.scrolled .nav-logo-text,
        .nav-split.scrolled .nav-link-light { color: var(--color-ink-strong); }
        .nav-split.scrolled .nav-search-btn { color: var(--color-ink-body); }
        .nav-split.scrolled .nav-burger { color: var(--color-ink-strong); }
        .nav-link-light {
            position: relative;
            color: rgba(255,255,255,0.85);
            font-size: 0.9375rem;
            font-weight: 500;
            padding: 0.25rem 0;
            transition: color 0.2s ease;
        }
        .nav-link-light:hover { color: #fff; }
        .nav-link-light.active { color: #fff; font-weight: 600; }
        .nav-link-light.active::after {
            content: '';
            position: absolute;
            left: 0;
            bottom: -4px;
            width: 100%;
            height: 2px;
            background: var(--brand-gradient);
            border-radius: 2px;
        }
        .nav-split.scrolled .nav-link-light:hover { color: var(--color-primary); }
        .nav-split.scrolled .nav-link-light.active { color: var(--color-primary); }
        .nav-search-btn { color: rgba(255,255,255,0.8); }
        .nav-burger { color: rgba(255,255,255,0.9); }
        .search-wrap {
            z-index: 60;
            background: #fff;
            border-radius: 0.75rem;
            box-shadow: 0 4px 20px rgba(15,23,42,0.12);
            padding: 0.25rem;
        }
        .search-wrap.hidden { display: none; }

        /* TOC */
        .toc-item {
            padding: 0.5rem 0.75rem;
            border-radius: 0.75rem;
            font-size: 0.9375rem;
            color: var(--color-ink-body);
            transition: all 0.2s ease;
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }
        .toc-item:hover { background: #F1F5F9; color: var(--color-primary); }
        .toc-item.active-link {
            background: rgba(79,70,229,0.08);
            color: var(--color-primary);
            font-weight: 600;
        }
        .toc-scroll { -webkit-overflow-scrolling: touch; scrollbar-width: none; }
        .toc-scroll::-webkit-scrollbar { display: none; }

        /* 移动端抽屉 */
        .mobile-drawer {
            transition: opacity 0.25s ease;
            background: #fff;
        }
        .mobile-drawer.hidden { opacity: 0; pointer-events: none; }

        /* focus state */
        a:focus-visible, button:focus-visible {
            outline: 3px solid rgba(79,70,229,0.4);
            outline-offset: 2px;
            border-radius: 4px;
        }

        /* 图片淡入占位 */
        .img-cover {
            background: #E2E8F0;
            object-fit: cover;
        }

        /* 数据数字 */
        .stat-num {
            font-variant-numeric: tabular-nums;
            letter-spacing: -0.01em;
        }