:root {
    --color-primary: #18181b;
    --color-on-primary: #ffffff;
    --color-secondary: #3f3f46;
    --color-accent: #db2777;
    --color-accent-hover: #be185d;
    --color-background: #fafafa;
    --color-foreground: #09090b;
    --color-muted: #71717a;
    --color-muted-bg: #f4f4f5;
    --color-border: #e4e4e7;
    --color-surface: #ffffff;
    --color-destructive: #dc2626;
    --color-ring: #18181b;
    --color-success: #15803d;
    --shadow-soft: 0 10px 30px rgba(9, 9, 11, 0.06);
    --radius: 16px;
    --radius-sm: 10px;
    --font-display: "Noto Serif SC", "Newsreader", "Songti SC", serif;
    --font-body: "Noto Sans SC", "Roboto", "PingFang SC", "Microsoft YaHei", sans-serif;
    --space: 8px;
}

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

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    font-family: var(--font-body);
    font-size: 16px;
    line-height: 1.65;
    color: var(--color-foreground);
    background: var(--color-background);
}

a {
    color: var(--color-primary);
}

a:hover {
    color: var(--color-accent);
}

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

:focus-visible {
    outline: 2px solid var(--color-ring);
    outline-offset: 3px;
}

.skip-link {
    position: absolute;
    left: 12px;
    top: -48px;
    z-index: 2000;
    padding: 8px 14px;
    background: var(--color-primary);
    color: var(--color-on-primary);
    border-radius: 8px;
    text-decoration: none;
}

.skip-link:focus {
    top: 12px;
    color: var(--color-on-primary);
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 1030;
    background: rgba(250, 250, 250, 0.92);
    border-bottom: 1px solid var(--color-border);
    backdrop-filter: blur(12px);
}

.site-header .navbar {
    padding: 12px 0;
    background: transparent;
}

.site-brand {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    font-family: var(--font-display);
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-foreground) !important;
    letter-spacing: -0.02em;
}

.site-brand i {
    color: var(--color-accent);
}

.site-nav .nav-link {
    color: var(--color-secondary) !important;
    font-weight: 500;
    padding: 8px 14px !important;
    border-radius: 999px;
    transition: background 180ms ease, color 180ms ease;
}

.site-nav .nav-link:hover,
.site-nav .nav-link.active {
    color: var(--color-foreground) !important;
    background: var(--color-muted-bg);
}

.btn,
.badge,
.nav-link,
.page-link,
.tag-link {
    cursor: pointer;
    transition: background-color 180ms ease, color 180ms ease, border-color 180ms ease, transform 180ms ease;
}

.btn-primary {
    background: var(--color-primary);
    border-color: var(--color-primary);
    color: var(--color-on-primary);
    border-radius: 999px;
    padding: 8px 18px;
    font-weight: 500;
}

.btn-primary:hover,
.btn-primary:focus {
    background: var(--color-secondary);
    border-color: var(--color-secondary);
    color: var(--color-on-primary);
}

.btn-accent,
.btn-light {
    background: var(--color-accent);
    border-color: var(--color-accent);
    color: #fff;
    border-radius: 999px;
    font-weight: 600;
}

.btn-accent:hover,
.btn-light:hover {
    background: var(--color-accent-hover);
    border-color: var(--color-accent-hover);
    color: #fff;
}

.btn-outline-secondary,
.btn-outline-danger {
    border-radius: 999px;
}

.site-hero {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    box-shadow: var(--shadow-soft);
    padding: 40px 36px;
    margin-bottom: 28px;
}

.site-hero h1,
.page-hero h1,
.article-page h1,
.card-title,
.sidebar h5 {
    font-family: var(--font-display);
    letter-spacing: -0.03em;
    color: var(--color-foreground);
}

.site-hero h1 {
    font-size: clamp(2rem, 4vw, 3rem);
    font-weight: 700;
    margin-bottom: 12px;
}

.site-hero .lead {
    color: var(--color-secondary);
    max-width: 42rem;
    margin-bottom: 0;
}

.page-hero,
.article-card,
.article-page,
.sidebar,
.card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    box-shadow: var(--shadow-soft);
}

.article-card {
    overflow: hidden;
    transition: transform 180ms ease, box-shadow 180ms ease;
}

.article-card .card-body,
.article-page .card-body,
.page-hero .card-body,
.sidebar {
    padding: 22px;
}

.article-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 16px 40px rgba(9, 9, 11, 0.08);
}

.article-card .card-title,
.article-card .card-title.h5 {
    font-size: 1.15rem;
    line-height: 1.4;
    margin-bottom: 10px;
}

.article-card .card-title a,
.article-card h3 a,
.article-card h5 a,
.article-card h6 a,
.card .card-title a {
    color: var(--color-foreground);
    text-decoration: none;
}

.article-card .card-title a:hover,
.article-card h3 a:hover {
    color: var(--color-accent);
}

.article-meta,
.text-muted {
    color: var(--color-muted) !important;
    font-size: 0.92rem;
}

.category-badge,
.badge.category-badge {
    background: var(--color-primary) !important;
    color: #fff;
    border-radius: 999px;
    font-weight: 500;
}

.tag-link,
.badge.bg-light,
.badge.bg-secondary {
    background: var(--color-muted-bg) !important;
    color: var(--color-secondary) !important;
    border-radius: 999px;
    font-weight: 500;
    padding: 6px 10px;
}

.tag-link:hover,
.badge.bg-secondary:hover,
.badge.bg-light:hover {
    background: var(--color-primary) !important;
    color: #fff !important;
}

.tag-link.bg-primary,
.badge.bg-primary {
    background: var(--color-primary) !important;
    color: #fff !important;
}

.card-header {
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    padding: 16px 22px;
}

.card-header h4,
.card-header h5 {
    font-family: var(--font-display);
    font-size: 1.1rem;
    margin: 0;
}

.card.border-0.bg-light,
.bg-light {
    background: var(--color-muted-bg) !important;
    box-shadow: none;
}

.navbar-toggler {
    border: 1px solid var(--color-border);
    border-radius: 10px;
    padding: 8px 10px;
}

.navbar-toggler:focus {
    box-shadow: 0 0 0 3px rgba(24, 24, 27, 0.12);
}

.btn-sm {
    min-height: 36px;
    padding: 6px 14px;
}

.sidebar h5 {
    font-size: 1.05rem;
    margin-bottom: 14px;
}

.sidebar .list-unstyled li {
    padding: 8px 0;
    border-bottom: 1px solid var(--color-border);
}

.sidebar .list-unstyled li:last-child {
    border-bottom: 0;
}

.sidebar hr {
    border-color: var(--color-border);
    opacity: 1;
}

.sidebar a {
    text-decoration: none;
    color: var(--color-secondary);
}

.sidebar a:hover {
    color: var(--color-accent);
}

.article-page {
    padding: 8px 4px 16px;
}

.article-page h1 {
    font-size: clamp(1.8rem, 3vw, 2.5rem);
    line-height: 1.25;
    margin-bottom: 12px;
}

.article-content {
    font-size: 1.0625rem;
    line-height: 1.8;
    color: #18181b;
    max-width: 72ch;
}

.article-content h2,
.article-content h3 {
    font-family: var(--font-display);
    margin-top: 1.6em;
    margin-bottom: 0.6em;
}

.article-content p {
    margin-bottom: 1.1em;
}

.article-content ul,
.article-content ol {
    padding-left: 1.4em;
    margin-bottom: 1.1em;
}

.article-content li {
    margin-bottom: 0.45em;
}

.article-content a {
    text-decoration: underline;
    text-underline-offset: 3px;
}

.article-content img {
    border-radius: 12px;
}

.breadcrumb {
    background: transparent;
    padding: 0;
    margin: 16px 0 0;
}

.breadcrumb-item a {
    color: var(--color-muted);
    text-decoration: none;
}

.breadcrumb-item.active {
    color: var(--color-foreground);
}

.pagination .page-link {
    color: var(--color-primary);
    border-color: var(--color-border);
    border-radius: 10px;
    margin: 0 3px;
}

.pagination .page-item.active .page-link {
    background: var(--color-primary);
    border-color: var(--color-primary);
    color: #fff;
}

.site-footer {
    background: var(--color-primary);
    color: #e4e4e7;
    margin-top: 64px;
    padding: 48px 0 28px;
}

.site-footer h5,
.site-footer h6 {
    font-family: var(--font-display);
    color: #fff;
}

.site-footer a {
    color: #d4d4d8;
    text-decoration: none;
}

.site-footer a:hover {
    color: #fff;
}

.site-footer hr {
    border-color: #3f3f46;
}

.mobile-bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: rgba(250, 250, 250, 0.94);
    backdrop-filter: blur(12px);
    border-top: 1px solid var(--color-border);
    padding: 12px 16px calc(12px + env(safe-area-inset-bottom));
    z-index: 1000;
    text-align: center;
}

.mobile-platform-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    background: var(--color-accent);
    color: #fff;
    text-decoration: none;
    padding: 12px 24px;
    border-radius: 999px;
    font-weight: 600;
    width: 100%;
    max-width: 320px;
    min-height: 48px;
}

.mobile-platform-btn:hover {
    background: var(--color-accent-hover);
    color: #fff;
    text-decoration: none;
}

#back-to-top {
    position: fixed;
    right: 20px;
    bottom: 100px;
    z-index: 999;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    display: none;
    padding: 0;
    background: var(--color-primary);
    border: none;
    color: #fff;
}

.error-page {
    font-family: var(--font-display);
    font-size: clamp(4rem, 12vw, 7rem);
    color: var(--color-primary);
    line-height: 1;
    font-weight: 700;
    padding: 28px 0 8px;
}

.site-main {
    min-height: 48vh;
}

.empty-state {
    text-align: center;
    padding: 40px 20px;
    color: var(--color-secondary);
    background: var(--color-surface);
    border: 1px dashed var(--color-border);
    border-radius: var(--radius);
}

@media (max-width: 991px) {
    .site-nav .btn-accent {
        margin-top: 12px;
        width: 100%;
    }

    .site-nav .nav-link {
        padding: 12px 14px !important;
        min-height: 44px;
    }
}

@media (max-width: 768px) {
    body {
        padding-bottom: 88px;
    }

    .site-hero {
        padding: 28px 20px;
    }

    .article-content {
        max-width: none;
    }
}

@media (min-width: 769px) {
    .mobile-bottom-nav {
        display: none;
    }
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
        animation: none !important;
        transition: none !important;
    }
}