/* ===== 全局变量与重置 ===== */
:root {
    --bg-light: #f8fafc;
    --bg-dark: #0f172a;
    --text-light: #1F2937;
    --text-dark: #E2E8F0;
    --heading-light: #111827;
    --heading-dark: #F8FAFC;
    --muted-light: #475569;
    --muted-dark: #94A3B8;
    --card-bg-light: rgba(255, 255, 255, 0.85);
    --card-bg-dark: rgba(30, 41, 59, 0.85);
    --border-light: rgba(209, 213, 219, 0.6);
    --border-dark: rgba(51, 65, 85, 0.6);
    --accent: #2563eb;
    --accent-dark: #3b82f6;
    --accent-glow: rgba(59, 130, 246, 0.3);
    --link-light: #1e40af;
    --link-dark: #93c5fd;
    --btn-bg-light: #1F2937;
    --btn-text-light: #ffffff;
    --btn-bg-dark: #3b82f6;
    --btn-text-dark: #0f172a;
    --nav-bg-light: rgba(255, 255, 255, 0.8);
    --nav-bg-dark: rgba(15, 23, 42, 0.8);
    --footer-bg-light: #111827;
    --footer-text-light: #E2E8F0;
    --footer-bg-dark: #020617;
    --footer-text-dark: #cbd5e1;
    --gradient-primary: linear-gradient(135deg, #1e3a8a 0%, #2563eb 50%, #3b82f6 100%);
    --gradient-banner: linear-gradient(135deg, #0f172a 0%, #1e3a8a 40%, #2563eb 100%);
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.12);
    --shadow-glow: 0 0 20px var(--accent-glow);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-full: 50%;
    --blur-md: blur(12px);
    --blur-lg: blur(20px);
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif;
    background-color: var(--bg-light);
    background-image: 
        radial-gradient(circle at 10% 20%, rgba(37, 99, 235, 0.04) 0%, transparent 40%),
        radial-gradient(circle at 90% 70%, rgba(59, 130, 246, 0.04) 0%, transparent 40%);
    color: var(--text-light);
    line-height: 1.7;
    transition: background-color var(--transition-normal), color var(--transition-normal);
    overflow-x: hidden;
}

body.dark-mode {
    background-color: var(--bg-dark);
    background-image: 
        radial-gradient(circle at 10% 20%, rgba(37, 99, 235, 0.08) 0%, transparent 40%),
        radial-gradient(circle at 90% 70%, rgba(59, 130, 246, 0.08) 0%, transparent 40%);
    color: var(--text-dark);
}

/* 滚动条样式 */
::-webkit-scrollbar {
    width: 10px;
    height: 10px;
}

::-webkit-scrollbar-track {
    background: transparent;
}

::-webkit-scrollbar-thumb {
    background: linear-gradient(135deg, var(--accent), var(--accent-dark));
    border-radius: 10px;
    border: 2px solid transparent;
    background-clip: padding-box;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--accent-dark);
    background-clip: padding-box;
    border: 2px solid transparent;
}

/* 标题层级 */
h1, h2, h3, h4 {
    font-weight: 700;
    line-height: 1.3;
    color: var(--heading-light);
    letter-spacing: -0.02em;
    transition: color var(--transition-normal);
}

body.dark-mode h1,
body.dark-mode h2,
body.dark-mode h3,
body.dark-mode h4 {
    color: var(--heading-dark);
}

h1 {
    font-size: clamp(1.8rem, 4vw, 2.8rem);
    margin-bottom: 1.2rem;
    background: linear-gradient(135deg, #ffffff 0%, #e2e8f0 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-shadow: 0 2px 20px rgba(0, 0, 0, 0.3);
}

h2 {
    font-size: clamp(1.5rem, 3vw, 2.2rem);
    margin: 3rem 0 1.5rem;
    border-left: 6px solid var(--accent);
    padding-left: 1.2rem;
    position: relative;
    transition: border-color var(--transition-normal);
}

h2::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: -8px;
    width: 60px;
    height: 3px;
    background: var(--gradient-primary);
    border-radius: 3px;
    opacity: 0.6;
}

h3 {
    font-size: clamp(1.2rem, 2vw, 1.5rem);
    margin: 2rem 0 0.8rem;
    position: relative;
}

h4 {
    font-size: 1.1rem;
    margin: 1.5rem 0 0.5rem;
    color: var(--muted-light);
    transition: color var(--transition-normal);
}

body.dark-mode h4 {
    color: var(--muted-dark);
}

p {
    margin-bottom: 1.2rem;
    color: var(--text-light);
    transition: color var(--transition-normal);
}

body.dark-mode p {
    color: var(--text-dark);
}

a {
    color: var(--link-light);
    text-decoration: none;
    font-weight: 500;
    transition: color var(--transition-fast), text-decoration var(--transition-fast);
    position: relative;
}

body.dark-mode a {
    color: var(--link-dark);
}

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

/* 容器 */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
    width: 100%;
}

/* ===== 导航栏 ===== */
.site-header {
    background-color: var(--nav-bg-light);
    backdrop-filter: var(--blur-md);
    -webkit-backdrop-filter: var(--blur-md);
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.08);
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: background-color var(--transition-normal), box-shadow var(--transition-normal);
    border-bottom: 1px solid var(--border-light);
}

body.dark-mode .site-header {
    background-color: var(--nav-bg-dark);
    border-bottom-color: var(--border-dark);
}

.site-header.scrolled {
    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.15);
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 1.5rem;
    max-width: 1200px;
    margin: 0 auto;
}

.logo {
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--heading-light);
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.03em;
    transition: transform var(--transition-fast);
    cursor: pointer;
    position: relative;
}

.logo::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--gradient-primary);
    transition: width var(--transition-normal);
}

.logo:hover::after {
    width: 100%;
}

body.dark-mode .logo {
    color: var(--heading-dark);
}

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

.nav-links a {
    color: var(--text-light);
    font-weight: 500;
    position: relative;
    padding: 0.5rem 0;
    transition: color var(--transition-fast);
}

body.dark-mode .nav-links a {
    color: var(--text-dark);
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--gradient-primary);
    transition: width var(--transition-normal);
    border-radius: 2px;
}

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

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

/* 按钮 */
.btn {
    display: inline-block;
    background: var(--gradient-primary);
    color: var(--btn-text-light);
    padding: 0.7rem 1.6rem;
    border-radius: var(--radius-sm);
    font-weight: 600;
    border: none;
    cursor: pointer;
    transition: all var(--transition-normal);
    box-shadow: 0 4px 15px rgba(37, 99, 235, 0.3);
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.2);
    transform: translate(-50%, -50%);
    transition: width 0.6s ease, height 0.6s ease;
}

.btn:hover::before {
    width: 300px;
    height: 300px;
}

body.dark-mode .btn {
    background: var(--gradient-primary);
    color: var(--btn-text-dark);
    box-shadow: 0 4px 20px rgba(59, 130, 246, 0.4);
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(37, 99, 235, 0.4);
    opacity: 1;
}

/* 移动菜单按钮 */
.menu-toggle {
    display: none;
    background: var(--card-bg-light);
    border: 1px solid var(--border-light);
    border-radius: var(--radius-sm);
    padding: 0.5rem 1rem;
    font-size: 1.3rem;
    cursor: pointer;
    color: var(--text-light);
    transition: all var(--transition-fast);
    backdrop-filter: var(--blur-md);
}

body.dark-mode .menu-toggle {
    background: var(--card-bg-dark);
    border-color: var(--border-dark);
    color: var(--text-dark);
}

.menu-toggle:hover {
    border-color: var(--accent);
    color: var(--accent);
    transform: scale(1.05);
}

/* 移动端菜单 */
.mobile-menu {
    display: none;
    flex-direction: column;
    background-color: var(--nav-bg-light);
    backdrop-filter: var(--blur-lg);
    -webkit-backdrop-filter: var(--blur-lg);
    padding: 1.5rem;
    gap: 1rem;
    border-top: 1px solid var(--border-light);
    animation: slideDown 0.3s ease;
}

body.dark-mode .mobile-menu {
    background-color: var(--nav-bg-dark);
    border-top-color: var(--border-dark);
}

.mobile-menu a {
    color: var(--text-light);
    padding: 0.8rem 1rem;
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
    font-weight: 500;
}

body.dark-mode .mobile-menu a {
    color: var(--text-dark);
}

.mobile-menu a:hover {
    background: rgba(37, 99, 235, 0.1);
    color: var(--accent);
    padding-left: 1.5rem;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ===== Banner区域 ===== */
.banner {
    background: var(--gradient-banner);
    color: white;
    padding: 4rem 2.5rem;
    border-radius: var(--radius-lg);
    margin: 2.5rem 0;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    animation: fadeInUp 1s ease;
}

.banner::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, rgba(255, 255, 255, 0.1) 0%, transparent 70%);
    animation: float 8s ease-in-out infinite;
}

.banner::after {
    content: '';
    position: absolute;
    bottom: -30%;
    left: -10%;
    width: 300px;
    height: 300px;
    background: radial-gradient(circle, rgba(59, 130, 246, 0.2) 0%, transparent 70%);
    animation: float 12s ease-in-out infinite reverse;
}

.banner h1 {
    color: white;
    text-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
    position: relative;
    z-index: 1;
}

.banner p {
    color: rgba(255, 255, 255, 0.95);
    font-size: 1.3rem;
    position: relative;
    z-index: 1;
    max-width: 800px;
}

/* ===== 卡片网格 ===== */
.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 2rem;
    margin: 2.5rem 0;
}

.card {
    background-color: var(--card-bg-light);
    backdrop-filter: var(--blur-md);
    -webkit-backdrop-filter: var(--blur-md);
    border: 1px solid var(--border-light);
    border-radius: var(--radius-md);
    padding: 2rem;
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    animation: fadeInUp 0.6s ease both;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 3px;
    background: var(--gradient-primary);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform var(--transition-normal);
}

.card:hover::before {
    transform: scaleX(1);
}

body.dark-mode .card {
    background-color: var(--card-bg-dark);
    border-color: var(--border-dark);
}

.card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    border-color: var(--accent);
}

.card h3 {
    margin-top: 0;
    color: var(--heading-light);
    font-size: 1.3rem;
    transition: color var(--transition-normal);
}

body.dark-mode .card h3 {
    color: var(--heading-dark);
}

.card h3:hover {
    color: var(--accent);
}

.card p {
    margin-bottom: 0.8rem;
}

.card a {
    display: inline-block;
    margin-top: 0.5rem;
    font-weight: 600;
}

/* ===== FAQ样式 ===== */
.faq-item {
    border-bottom: 1px solid var(--border-light);
    padding: 1.2rem 0;
    transition: background-color var(--transition-fast);
    border-radius: var(--radius-sm);
    padding-left: 1rem;
    padding-right: 1rem;
}

body.dark-mode .faq-item {
    border-color: var(--border-dark);
}

.faq-item:hover {
    background: rgba(37, 99, 235, 0.04);
}

.faq-question {
    font-weight: 700;
    font-size: 1.1rem;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--heading-light);
    padding: 0.5rem 0;
    transition: color var(--transition-fast);
    user-select: none;
}

body.dark-mode .faq-question {
    color: var(--heading-dark);
}

.faq-question::after {
    content: '+';
    font-size: 1.5rem;
    font-weight: 300;
    color: var(--accent);
    transition: transform var(--transition-normal);
    flex-shrink: 0;
    margin-left: 1rem;
}

.faq-item.active .faq-question::after {
    transform: rotate(45deg);
}

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

.faq-answer {
    margin-top: 0.8rem;
    color: var(--text-light);
    padding: 1rem;
    background: rgba(37, 99, 235, 0.05);
    border-radius: var(--radius-sm);
    border-left: 3px solid var(--accent);
    animation: fadeIn 0.3s ease;
}

body.dark-mode .faq-answer {
    color: var(--text-dark);
    background: rgba(59, 130, 246, 0.1);
}

/* ===== 表格 ===== */
.table-wrap {
    overflow-x: auto;
    margin: 2rem 0;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
}

table {
    width: 100%;
    border-collapse: collapse;
    background-color: var(--card-bg-light);
    backdrop-filter: var(--blur-md);
    border-radius: var(--radius-md);
    overflow: hidden;
}

body.dark-mode table {
    background-color: var(--card-bg-dark);
}

th, td {
    border: 1px solid var(--border-light);
    padding: 1rem 1.2rem;
    text-align: left;
    color: var(--text-light);
    transition: background-color var(--transition-fast);
}

body.dark-mode th, body.dark-mode td {
    border-color: var(--border-dark);
    color: var(--text-dark);
}

th {
    background: var(--gradient-primary);
    color: white;
    font-weight: 700;
    letter-spacing: 0.02em;
}

body.dark-mode th {
    background: linear-gradient(135deg, #1e293b, #334155);
    color: white;
}

tr:hover td {
    background: rgba(37, 99, 235, 0.05);
}

/* ===== 页脚 ===== */
.site-footer {
    background-color: var(--footer-bg-light);
    color: var(--footer-text-light);
    padding: 4rem 0 2rem;
    margin-top: 5rem;
    position: relative;
    overflow: hidden;
}

body.dark-mode .site-footer {
    background-color: var(--footer-bg-dark);
    color: var(--footer-text-dark);
}

.site-footer::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: var(--gradient-primary);
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 2.5rem;
    margin-bottom: 2rem;
}

.footer-grid a {
    color: var(--footer-text-light);
    transition: all var(--transition-fast);
    display: inline-block;
    padding: 0.2rem 0;
}

body.dark-mode .footer-grid a {
    color: var(--footer-text-dark);
}

.footer-grid a:hover {
    color: var(--accent);
    transform: translateX(5px);
}

.footer-grid h4 {
    color: inherit;
    font-size: 1.1rem;
    margin-bottom: 1rem;
    position: relative;
    padding-bottom: 0.5rem;
}

.footer-grid h4::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 40px;
    height: 2px;
    background: var(--gradient-primary);
}

.footer-grid ul {
    list-style: none;
    color: inherit;
}

.footer-grid ul li {
    margin-bottom: 0.5rem;
}

/* ===== 返回顶部 ===== */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    background: var(--gradient-primary);
    color: white;
    border: none;
    border-radius: var(--radius-full);
    width: 52px;
    height: 52px;
    font-size: 1.5rem;
    cursor: pointer;
    display: none;
    z-index: 999;
    box-shadow: var(--shadow-lg);
    transition: all var(--transition-normal);
    animation: fadeIn 0.3s ease;
}

.back-to-top:hover {
    transform: translateY(-4px) scale(1.05);
    box-shadow: 0 8px 30px rgba(37, 99, 235, 0.4);
}

/* ===== 工具类 ===== */
.text-muted {
    color: var(--muted-light);
    font-size: 0.9rem;
}

body.dark-mode .text-muted {
    color: var(--muted-dark);
}

/* ===== 动画 ===== */
@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

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

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

/* ===== 响应式 ===== */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    .menu-toggle {
        display: block;
    }
    
    .mobile-menu.open {
        display: flex;
    }
    
    h1 {
        font-size: 1.8rem;
    }
    
    h2 {
        font-size: 1.5rem;
    }
    
    .banner {
        padding: 2.5rem 1.5rem;
    }
    
    .banner p {
        font-size: 1.1rem;
    }
    
    .card-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .back-to-top {
        bottom: 20px;
        right: 20px;
        width: 44px;
        height: 44px;
        font-size: 1.2rem;
    }
    
    .container {
        padding: 0 1rem;
    }
    
    .table-wrap {
        margin: 1.5rem -0.5rem;
    }
    
    th, td {
        padding: 0.8rem;
    }
}

@media (max-width: 480px) {
    .logo {
        font-size: 1.5rem;
    }
    
    .nav-container {
        padding: 0.8rem 1rem;
    }
    
    .banner {
        margin: 1.5rem 0;
        padding: 2rem 1.2rem;
    }
    
    .card {
        padding: 1.5rem;
    }
    
    .footer-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
}

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

/* 无障碍 */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* 焦点可见性 */
a:focus-visible,
button:focus-visible {
    outline: 3px solid var(--accent);
    outline-offset: 2px;
    border-radius: 4px;
}