```css
/* 全局颜色变量 —— 保证高可读性对比度 */
:root {
    --bg-body: #F8FAFC;
    --bg-card: #FFFFFF;
    --bg-header: #FFFFFF;
    --bg-footer: #1E293B;
    --text-primary: #1F2937;
    --text-secondary: #334155;
    --text-heading: #0B1B2A;
    --text-footer: #E2E8F0;
    --text-footer-head: #FFFFFF;
    --accent: #B91C1C;
    --accent-dark: #7F1D1D;
    --border-light: #CBD5E1;
    --shadow-sm: 0 2px 8px rgba(0,0,0,0.05);
    --shadow-hover: 0 8px 20px rgba(0,0,0,0.1);
    --btn-text: #FFFFFF;
    --glass-bg: rgba(255, 255, 255, 0.7);
    --glass-border: rgba(255, 255, 255, 0.3);
}

/* 暗黑模式变量 */
[data-theme="dark"] {
    --bg-body: #0F172A;
    --bg-card: #1E293B;
    --bg-header: #1E293B;
    --bg-footer: #0B1120;
    --text-primary: #E2E8F0;
    --text-secondary: #CBD5E1;
    --text-heading: #F8FAFC;
    --text-footer: #CBD5E1;
    --text-footer-head: #FFFFFF;
    --border-light: #334155;
    --accent: #F87171;
    --accent-dark: #DC2626;
    --btn-text: #0F172A;
    --glass-bg: rgba(30, 41, 59, 0.7);
    --glass-border: rgba(255, 255, 255, 0.1);
}

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

html { scroll-behavior: smooth; }

body {
    font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, 'Noto Sans', sans-serif;
    background-color: var(--bg-body);
    color: var(--text-primary);
    line-height: 1.7;
    transition: background-color 0.3s ease, color 0.3s ease;
    -webkit-font-smoothing: antialiased;
    background-image: 
        radial-gradient(circle at 10% 20%, rgba(185, 28, 28, 0.03) 0%, transparent 50%),
        radial-gradient(circle at 90% 80%, rgba(185, 28, 28, 0.03) 0%, transparent 50%);
    background-attachment: fixed;
}

/* 标题层级颜色 */
h1, h2, h3, h4 {
    color: var(--text-heading);
    font-weight: 600;
    line-height: 1.3;
}

h1 { font-size: 2.4rem; margin-bottom: 1rem; }
h2 { font-size: 2rem; margin-top: 2rem; margin-bottom: 1rem; border-left: 6px solid var(--accent); padding-left: 1rem; }
h3 { font-size: 1.5rem; margin-top: 1.5rem; margin-bottom: 0.75rem; }
h4 { font-size: 1.2rem; margin-top: 1.2rem; margin-bottom: 0.5rem; }

p { color: var(--text-primary); margin-bottom: 1.2rem; }

a {
    color: var(--accent);
    text-decoration: underline;
    text-underline-offset: 3px;
    transition: color 0.2s;
}

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

ul, ol { margin-left: 1.5rem; margin-bottom: 1.2rem; }

li { margin-bottom: 0.5rem; color: var(--text-primary); }

.container { max-width: 1280px; margin: 0 auto; padding: 0 1.5rem; }

/* 导航 */
.site-header {
    background-color: var(--bg-header);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 100;
    transition: background-color 0.3s;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    background-color: rgba(255, 255, 255, 0.85);
}

[data-theme="dark"] .site-header {
    background-color: rgba(30, 41, 59, 0.85);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}

.logo {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--text-heading);
    text-decoration: none;
    letter-spacing: 1px;
    transition: transform 0.2s;
}

.logo:hover { transform: scale(1.05); }

.logo span { color: var(--accent); }

.nav-links {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.nav-links a {
    color: var(--text-primary);
    text-decoration: none;
    font-weight: 500;
    font-size: 1rem;
    transition: opacity 0.2s;
    position: relative;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--accent);
    transition: width 0.3s;
}

.nav-links a:hover {
    color: var(--accent);
    text-decoration: none;
}

.nav-links a:hover::after { width: 100%; }

.menu-toggle {
    display: none;
    background: none;
    border: none;
    font-size: 1.8rem;
    cursor: pointer;
    color: var(--text-primary);
}

@media (max-width: 800px) {
    .nav-links {
        display: none;
        flex-direction: column;
        position: absolute;
        top: 70px;
        left: 0;
        right: 0;
        background: var(--bg-header);
        padding: 1.5rem;
        box-shadow: var(--shadow-sm);
        backdrop-filter: blur(10px);
        -webkit-backdrop-filter: blur(10px);
    }
    .nav-links.open { display: flex; }
    .menu-toggle { display: block; }
}

/* 按钮 */
.btn {
    display: inline-block;
    background-color: var(--accent);
    color: var(--btn-text);
    padding: 0.8rem 1.8rem;
    border-radius: 40px;
    text-decoration: none;
    font-weight: 500;
    border: none;
    cursor: pointer;
    transition: background-color 0.2s, transform 0.1s, box-shadow 0.2s;
    box-shadow: 0 4px 12px rgba(185, 28, 28, 0.2);
}

.btn:hover {
    background-color: var(--accent-dark);
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(185, 28, 28, 0.3);
}

.btn-outline {
    background: transparent;
    border: 2px solid var(--accent);
    color: var(--accent);
}

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

/* 卡片 */
.card {
    background: var(--bg-card);
    border-radius: 20px;
    padding: 2rem;
    box-shadow: var(--shadow-sm);
    transition: box-shadow 0.3s, transform 0.3s;
    border: 1px solid var(--border-light);
    overflow: hidden;
    position: relative;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--accent), transparent);
    opacity: 0;
    transition: opacity 0.3s;
}

.card:hover {
    box-shadow: var(--shadow-hover);
    transform: translateY(-4px);
}

.card:hover::before { opacity: 1; }

.grid-2 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
}

.grid-3 {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
}

@media (max-width: 800px) {
    .grid-2, .grid-3 { grid-template-columns: 1fr; }
}

/* banner */
.banner {
    background: linear-gradient(135deg, #1E293B 0%, #0F172A 50%, #1E293B 100%);
    color: #F1F5F9;
    padding: 5rem 0;
    border-radius: 0 0 40px 40px;
    position: relative;
    overflow: hidden;
}

.banner::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 60%;
    height: 200%;
    background: radial-gradient(circle, rgba(248, 113, 113, 0.1) 0%, transparent 70%);
    animation: bannerFloat 8s ease-in-out infinite;
}

@keyframes bannerFloat {
    0%, 100% { transform: translateY(0) rotate(0deg); }
    50% { transform: translateY(-20px) rotate(5deg); }
}

.banner h1 {
    color: #FFFFFF;
    font-size: 3rem;
    animation: fadeInUp 0.6s ease-out;
}

.banner p {
    color: #E2E8F0;
    font-size: 1.3rem;
    animation: fadeInUp 0.6s ease-out 0.2s both;
}

.banner .btn {
    background: #F87171;
    color: #0F172A;
    animation: fadeInUp 0.6s ease-out 0.4s both;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* 文章卡片 */
.article-card {
    padding: 1.5rem;
    background: var(--bg-card);
    border-radius: 16px;
    border-left: 4px solid var(--accent);
    transition: transform 0.2s, box-shadow 0.2s;
    cursor: pointer;
}

.article-card:hover {
    transform: translateX(4px);
    box-shadow: var(--shadow-hover);
}

.article-card h3 { margin-top: 0; }

.article-card .meta {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.read-more {
    font-weight: 600;
    display: inline-block;
    transition: transform 0.2s;
}

.read-more:hover { transform: translateX(4px); }

/* FAQ */
.faq-item {
    border-bottom: 1px solid var(--border-light);
    padding: 1.2rem 0;
    transition: background-color 0.2s;
}

.faq-item:hover { background-color: rgba(185, 28, 28, 0.02); }

.faq-question {
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    font-weight: 600;
    color: var(--text-heading);
    user-select: none;
    transition: color 0.2s;
}

.faq-question:hover { color: var(--accent); }

.faq-answer {
    display: none;
    padding-top: 1rem;
    color: var(--text-primary);
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.faq-item.active .faq-answer { display: block; }
.faq-item.active .faq-icon { transform: rotate(45deg); }

.faq-icon {
    font-size: 1.8rem;
    line-height: 1;
    color: var(--accent);
    transition: transform 0.3s;
}

/* footer */
.site-footer {
    background-color: var(--bg-footer);
    color: var(--text-footer);
    padding: 3rem 0;
    margin-top: 4rem;
    border-radius: 40px 40px 0 0;
    position: relative;
}

.site-footer::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 2rem;
}

@media (max-width: 800px) {
    .footer-grid { grid-template-columns: 1fr 1fr; }
}

.site-footer h4 {
    color: var(--text-footer-head);
    margin-bottom: 1rem;
    border-left: none;
    padding-left: 0;
}

.site-footer a {
    color: var(--text-footer);
    text-decoration: underline;
    transition: color 0.2s;
}

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

.footer-bottom {
    border-top: 1px solid #334155;
    margin-top: 2rem;
    padding-top: 1.5rem;
    text-align: center;
}

/* 其他 */
.breadcrumb {
    display: flex;
    gap: 0.5rem;
    font-size: 0.9rem;
    margin-bottom: 1rem;
    color: var(--text-secondary);
    padding-top: 1rem;
}

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

.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    background: var(--accent);
    color: white;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    text-decoration: none;
    font-size: 1.8rem;
    box-shadow: var(--shadow-hover);
    transition: 0.2s;
    z-index: 1000;
}

.back-to-top:hover {
    background: var(--accent-dark);
    transform: translateY(-4px);
}

.dark-toggle {
    background: none;
    border: 2px solid var(--border-light);
    color: var(--text-primary);
    padding: 0.3rem 1rem;
    border-radius: 40px;
    cursor: pointer;
    font-weight: 500;
    transition: all 0.2s;
}

.dark-toggle:hover {
    border-color: var(--accent);
    color: var(--accent);
}

/* 表格 */
table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.5rem 0;
}

th, td {
    padding: 0.8rem 1rem;
    border: 1px solid var(--border-light);
    text-align: left;
}

th {
    background-color: var(--bg-card);
    color: var(--text-heading);
    font-weight: 600;
}

/* SVG 图片占位 */
.svg-placeholder {
    background-color: #E2E8F0;
    border-radius: 12px;
    width: 100%;
    height: 160px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #1F2937;
    font-weight: 500;
    transition: all 0.3s;
}

.svg-placeholder:hover {
    transform: scale(1.02);
    box-shadow: var(--shadow-sm);
}

[data-theme="dark"] .svg-placeholder {
    background-color: #334155;
    color: #E2E8F0;
}

/* 毛玻璃效果 */
.glass-effect {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: 20px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
}

/* 滚动动画 */
.reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.visible {
    opacity: 1;
    transform: translateY(0);
}

/* 卡片悬停增强 */
.card, .article-card {
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.card:hover, .article-card:hover {
    transform: translateY(-6px) scale(1.01);
}

/* 链接下划线动画 */
a:not(.btn):not(.logo):not(.back-to-top) {
    position: relative;
}

/* 响应式优化 */
@media (max-width: 600px) {
    h1 { font-size: 1.8rem; }
    h2 { font-size: 1.5rem; }
    h3 { font-size: 1.2rem; }
    
    .banner { padding: 3rem 0; }
    .banner h1 { font-size: 2rem; }
    .banner p { font-size: 1rem; }
    
    .card { padding: 1.5rem; }
    
    .back-to-top {
        width: 40px;
        height: 40px;
        font-size: 1.4rem;
        bottom: 1.5rem;
        right: 1.5rem;
    }
}

/* 暗色模式过渡 */
body, .site-header, .card, .article-card, .faq-item, .site-footer {
    transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
}

/* 滚动条美化 */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-body);
}

::-webkit-scrollbar-thumb {
    background: var(--accent);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--accent-dark);
}

/* 选中文字颜色 */
::selection {
    background: var(--accent);
    color: var(--btn-text);
}

/* 焦点样式增强 */
:focus {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}

:focus:not(:focus-visible) {
    outline: none;
}

/* 打印样式 */
@media print {
    .site-header, .site-footer, .back-to-top, .dark-toggle, .menu-toggle {
        display: none !important;
    }
    
    body {
        background: white;
        color: black;
    }
    
    .card {
        box-shadow: none;
        border: 1px solid #ccc;
    }
}

/* 性能优化：硬件加速 */
.card, .article-card, .btn {
    will-change: transform, box-shadow;
}

/* 减少动画偏好 */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}
```