:root {
    --brand-primary: #1e3a5f;
    --brand-secondary: #2c5282;
    --brand-accent: #e67e22;
    --brand-gradient: linear-gradient(135deg, #1e3a5f 0%, #2c5282 50%, #1e3a5f 100%);
    --brand-gradient-soft: linear-gradient(135deg, #e0e7ff 0%, #f0f4ff 50%, #e6f0fa 100%);
    --bg-body: #f8fafc;
    --bg-card: #ffffff;
    --bg-glass: rgba(255, 255, 255, 0.72);
    --bg-glass-border: rgba(255, 255, 255, 0.55);
    --bg-dark: #0f172a;
    --bg-dark-card: #1e293b;
    --text-primary: #17202a;
    --text-secondary: #334155;
    --text-muted: #4b5563;
    --text-light: #6b7280;
    --text-white: #ffffff;
    --text-dark-heading: #0f172a;
    --border-light: #e2e8f0;
    --border-dark: #334155;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.12);
    --shadow-glow: 0 8px 32px rgba(30, 58, 95, 0.18);
    --radius: 16px;
    --radius-sm: 10px;
    --radius-lg: 24px;
    --transition: all 0.28s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-bounce: all 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-body);
    color: var(--text-primary);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    transition: background-color 0.35s ease, color 0.35s ease;
    overflow-x: hidden;
}

body.dark-mode {
    --bg-body: #0f172a;
    --bg-card: #1e293b;
    --bg-glass: rgba(30, 41, 59, 0.78);
    --bg-glass-border: rgba(51, 65, 85, 0.6);
    --text-primary: #e5e7eb;
    --text-secondary: #e2e8f0;
    --text-muted: #cbd5e1;
    --text-light: #94a3b8;
    --text-dark-heading: #f8fafc;
    --border-light: #334155;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 8px 32px rgba(59, 130, 246, 0.22);
    --brand-gradient-soft: linear-gradient(135deg, #0f172a 0%, #1e293b 50%, #0f172a 100%);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ============ 头部导航 ============ */
.site-header {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: var(--bg-glass);
    -webkit-backdrop-filter: blur(18px) saturate(180%);
    backdrop-filter: blur(18px) saturate(180%);
    border-bottom: 1px solid var(--bg-glass-border);
    box-shadow: var(--shadow-sm);
    transition: background 0.35s ease, border-color 0.35s ease, box-shadow 0.35s ease;
}

body.dark-mode .site-header {
    background: rgba(30, 41, 59, 0.82);
    border-bottom-color: #334155;
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    text-decoration: none;
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--brand-primary);
    letter-spacing: -0.5px;
    transition: var(--transition);
}

.logo:hover {
    transform: scale(1.03);
}

.logo svg {
    width: 36px;
    height: 36px;
    transition: var(--transition-bounce);
}

.logo:hover svg {
    transform: rotate(-8deg) scale(1.08);
}

body.dark-mode .logo {
    color: #93c5fd;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 8px;
    list-style: none;
}

.nav-link {
    display: inline-block;
    padding: 8px 16px;
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    font-size: 0.95rem;
    border-radius: var(--radius-sm);
    transition: var(--transition);
    position: relative;
}

.nav-link::after {
    content: "";
    position: absolute;
    bottom: 4px;
    left: 50%;
    width: 0;
    height: 2px;
    background: var(--brand-gradient);
    border-radius: 2px;
    transition: var(--transition);
    transform: translateX(-50%);
}

.nav-link:hover {
    color: var(--brand-primary);
    background-color: rgba(30, 58, 95, 0.06);
}

.nav-link:hover::after {
    width: 60%;
}

body.dark-mode .nav-link {
    color: #e2e8f0;
}

body.dark-mode .nav-link:hover {
    color: #ffffff;
    background-color: #2d3748;
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 12px;
}

.search-box {
    position: relative;
}

.search-input {
    padding: 8px 14px 8px 36px;
    border: 1px solid var(--border-light);
    border-radius: 20px;
    font-size: 0.9rem;
    outline: none;
    width: 180px;
    transition: var(--transition);
    background-color: var(--bg-card);
    color: var(--text-primary);
    -webkit-backdrop-filter: blur(8px);
    backdrop-filter: blur(8px);
}

.search-input:focus {
    border-color: var(--brand-secondary);
    box-shadow: 0 0 0 3px rgba(44, 82, 130, 0.15);
    width: 220px;
}

.search-icon {
    position: absolute;
    left: 12px;
    top: 50%;
    transform: translateY(-50%);
    width: 16px;
    height: 16px;
    fill: var(--text-muted);
    pointer-events: none;
}

.theme-toggle {
    background: none;
    border: 1px solid var(--border-light);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition-bounce);
    color: var(--text-primary);
}

.theme-toggle:hover {
    background-color: rgba(30, 58, 95, 0.08);
    transform: rotate(20deg) scale(1.08);
    border-color: var(--brand-secondary);
}

body.dark-mode .theme-toggle:hover {
    background-color: #334155;
}

.theme-toggle svg {
    width: 20px;
    height: 20px;
    fill: currentColor;
}

.mobile-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
    color: var(--text-primary);
    transition: var(--transition);
}

.mobile-toggle:hover {
    transform: scale(1.1);
}

.mobile-toggle svg {
    width: 24px;
    height: 24px;
    fill: currentColor;
}

.mobile-menu {
    display: none;
    position: absolute;
    top: 70px;
    left: 0;
    right: 0;
    background: var(--bg-glass);
    -webkit-backdrop-filter: blur(20px) saturate(180%);
    backdrop-filter: blur(20px) saturate(180%);
    border-bottom: 1px solid var(--bg-glass-border);
    box-shadow: var(--shadow-md);
    z-index: 999;
    animation: slideDown 0.3s ease;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-12px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

.mobile-nav {
    list-style: none;
    padding: 8px 0;
}

.mobile-nav-link {
    display: block;
    padding: 14px 24px;
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    border-bottom: 1px solid var(--border-light);
    transition: var(--transition);
}

.mobile-nav-link:hover {
    background-color: rgba(30, 58, 95, 0.06);
    color: var(--brand-primary);
    padding-left: 32px;
}

body.dark-mode .mobile-menu {
    background: rgba(30, 41, 59, 0.92);
}

body.dark-mode .mobile-nav-link {
    color: #e2e8f0;
    border-bottom-color: #334155;
}

body.dark-mode .mobile-nav-link:hover {
    background-color: #2d3748;
    color: #ffffff;
}

/* ============ 面包屑 ============ */
.breadcrumb {
    padding: 16px 0;
    font-size: 0.9rem;
    color: var(--text-muted);
}

.breadcrumb a {
    color: var(--brand-secondary);
    text-decoration: none;
    transition: var(--transition);
}

.breadcrumb a:hover {
    text-decoration: underline;
    color: var(--brand-primary);
}

.breadcrumb span {
    margin: 0 6px;
}

/* ============ Hero 首屏 ============ */
.hero-section {
    background: var(--brand-gradient-soft);
    padding: 60px 0 70px;
    position: relative;
    overflow: hidden;
    transition: background 0.35s ease;
}

.hero-section::before {
    content: "";
    position: absolute;
    top: -50%;
    right: -20%;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(44, 82, 130, 0.12) 0%, transparent 70%);
    border-radius: 50%;
    pointer-events: none;
}

.hero-section::after {
    content: "";
    position: absolute;
    bottom: -40%;
    left: -10%;
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(230, 126, 34, 0.08) 0%, transparent 70%);
    border-radius: 50%;
    pointer-events: none;
}

.hero-inner {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 2.6rem;
    font-weight: 800;
    color: var(--text-dark-heading);
    line-height: 1.25;
    margin-bottom: 16px;
    letter-spacing: -0.5px;
}

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

.hero-subtitle {
    font-size: 1.15rem;
    color: var(--text-secondary);
    margin-bottom: 28px;
    line-height: 1.7;
}

.hero-actions {
    display: flex;
    gap: 14px;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 28px;
    font-size: 1rem;
    font-weight: 600;
    border-radius: var(--radius-sm);
    text-decoration: none;
    cursor: pointer;
    border: 2px solid transparent;
    transition: var(--transition);
    gap: 8px;
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    background: rgba(255, 255, 255, 0.18);
    border-radius: 50%;
    transform: translate(-50%, -50%);
    transition: width 0.5s ease, height 0.5s ease;
}

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

.btn-primary {
    background: var(--brand-gradient);
    color: #ffffff;
    border-color: transparent;
    box-shadow: 0 4px 14px rgba(30, 58, 95, 0.25);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-glow);
}

.btn-secondary {
    background-color: transparent;
    color: var(--brand-primary);
    border-color: var(--brand-primary);
}

.btn-secondary:hover {
    background: var(--brand-gradient);
    color: #ffffff;
    border-color: transparent;
    transform: translateY(-3px);
    box-shadow: var(--shadow-glow);
}

body.dark-mode .btn-secondary {
    color: #93c5fd;
    border-color: #3b82f6;
}

body.dark-mode .btn-secondary:hover {
    background: #3b82f6;
    color: #ffffff;
}

.hero-visual {
    display: flex;
    justify-content: center;
    align-items: center;
}

.hero-visual svg {
    width: 100%;
    max-width: 480px;
    height: auto;
    filter: drop-shadow(0 12px 32px rgba(30, 58, 95, 0.15));
    animation: floatY 5s ease-in-out infinite;
}

@keyframes floatY {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-12px);
    }
}

/* ============ 统计数据 ============ */
.stats-section {
    padding: 40px 0;
    background: var(--bg-glass);
    -webkit-backdrop-filter: blur(12px);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-light);
    transition: background 0.35s ease;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
    text-align: center;
}

.stat-item {
    padding: 16px;
    border-radius: var(--radius);
    transition: var(--transition);
}

.stat-item:hover {
    background: rgba(30, 58, 95, 0.04);
    transform: translateY(-4px);
}

body.dark-mode .stat-item:hover {
    background: rgba(59, 130, 246, 0.08);
}

.stat-number {
    font-size: 2.2rem;
    font-weight: 800;
    color: var(--brand-primary);
    line-height: 1.2;
    margin-bottom: 6px;
    background: var(--brand-gradient);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

body.dark-mode .stat-number {
    background: linear-gradient(135deg, #60a5fa 0%, #93c5fd 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.stat-label {
    font-size: 0.95rem;
    color: var(--text-muted);
    font-weight: 500;
}

/* ============ 通用区块 ============ */
.section {
    padding: 60px 0;
}

.section-header {
    text-align: center;
    margin-bottom: 44px;
}

.section-title {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-dark-heading);
    margin-bottom: 12px;
    letter-spacing: -0.3px;
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: "";
    position: absolute;
    bottom: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 48px;
    height: 3px;
    background: var(--brand-gradient);
    border-radius: 3px;
}

.section-subtitle {
    font-size: 1.05rem;
    color: var(--text-muted);
    max-width: 640px;
    margin: 16px auto 0;
}

/* ============ 卡片网格 ============ */
.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
}

.card {
    background: var(--bg-glass);
    -webkit-backdrop-filter: blur(12px) saturate(160%);
    backdrop-filter: blur(12px) saturate(160%);
    border: 1px solid var(--bg-glass-border);
    border-radius: var(--radius);
    padding: 28px 24px;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.card::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--brand-gradient);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.4s ease;
}

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

.card:hover {
    box-shadow: var(--shadow-glow);
    transform: translateY(-6px);
    border-color: var(--brand-secondary);
}

.card-icon {
    width: 48px;
    height: 48px;
    margin-bottom: 18px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #eef2ff 0%, #e0e7ff 100%);
    color: var(--brand-primary);
    transition: var(--transition-bounce);
}

.card:hover .card-icon {
    transform: scale(1.1) rotate(-6deg);
}

body.dark-mode .card-icon {
    background: linear-gradient(135deg, #1e3a5f 0%, #2c5282 100%);
    color: #93c5fd;
}

.card-icon svg {
    width: 26px;
    height: 26px;
    fill: currentColor;
}

.card-title {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--text-dark-heading);
    margin-bottom: 10px;
}

.card-text {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* ============ 关于品牌 ============ */
.about-section {
    background: var(--bg-glass);
    -webkit-backdrop-filter: blur(12px);
    backdrop-filter: blur(12px);
    border-top: 1px solid var(--border-light);
    border-bottom: 1px solid var(--border-light);
}

.about-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 48px;
    align-items: center;
}

.about-content h2 {
    font-size: 1.9rem;
    font-weight: 700;
    color: var(--text-dark-heading);
    margin-bottom: 18px;
}

.about-content p {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: 16px;
    line-height: 1.8;
}

.about-content ul {
    list-style: none;
    padding: 0;
}

.about-content li {
    padding: 6px 0 6px 28px;
    position: relative;
    color: var(--text-secondary);
    font-size: 0.98rem;
    transition: var(--transition);
}

.about-content li:hover {
    color: var(--brand-primary);
    transform: translateX(4px);
}

.about-content li::before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--brand-accent);
    font-weight: 700;
    font-size: 1.1rem;
}

.about-visual svg {
    width: 100%;
    max-width: 460px;
    height: auto;
    display: block;
    margin: 0 auto;
    filter: drop-shadow(0 12px 32px rgba(30, 58, 95, 0.12));
}

/* ============ 文章列表 ============ */
.article-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 24px;
}

.article-card {
    background: var(--bg-glass);
    -webkit-backdrop-filter: blur(12px) saturate(160%);
    backdrop-filter: blur(12px) saturate(160%);
    border: 1px solid var(--bg-glass-border);
    border-radius: var(--radius);
    padding: 24px;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    position: relative;
    overflow: hidden;
}

.article-card::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--brand-gradient);
    transform: scaleX(0);
    transform-origin: right;
    transition: transform 0.4s ease;
}

.article-card:hover::after {
    transform: scaleX(1);
}

.article-card:hover {
    box-shadow: var(--shadow-glow);
    border-color: var(--brand-secondary);
    transform: translateY(-4px);
}

.article-tag {
    display: inline-block;
    background: linear-gradient(135deg, #eef2ff 0%, #e0e7ff 100%);
    color: var(--brand-primary);
    font-size: 0.78rem;
    font-weight: 600;
    padding: 4px 12px;
    border-radius: 20px;
    margin-bottom: 12px;
    width: fit-content;
    transition: var(--transition);
}

.article-card:hover .article-tag {
    background: var(--brand-gradient);
    color: #ffffff;
}

body.dark-mode .article-tag {
    background: linear-gradient(135deg, #1e3a5f 0%, #2c5282 100%);
    color: #93c5fd;
}

.article-title {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-dark-heading);
    margin-bottom: 10px;
    line-height: 1.4;
    transition: var(--transition);
}

.article-card:hover .article-title {
    color: var(--brand-secondary);
}

body.dark-mode .article-card:hover .article-title {
    color: #93c5fd;
}

.article-meta {
    font-size: 0.82rem;
    color: var(--text-light);
    margin-bottom: 10px;
}

.article-summary {
    font-size: 0.93rem;
    color: var(--text-secondary);
    line-height: 1.7;
    flex: 1;
    margin-bottom: 14px;
}

.article-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    color: var(--brand-secondary);
    font-weight: 600;
    font-size: 0.9rem;
    text-decoration: none;
    transition: var(--transition);
}

.article-link:hover {
    color: var(--brand-primary);
    gap: 12px;
}

.article-link svg {
    width: 16px;
    height: 16px;
    fill: currentColor;
    transition: var(--transition);
}

.article-link:hover svg {
    transform: translateX(4px);
}

/* ============ FAQ ============ */
.faq-section {
    background: var(--bg-glass);
    -webkit-backdrop-filter: blur(12px);
    backdrop-filter: blur(12px);
    border-top: 1px solid var(--border-light);
    border-bottom: 1px solid var(--border-light);
}

.faq-list {
    max-width: 860px;
    margin: 0 auto;
}

.faq-item {
    border: 1px solid var(--border-light);
    border-radius: var(--radius-sm);
    margin-bottom: 12px;
    overflow: hidden;
    background: var(--bg-card);
    transition: var(--transition);
}

.faq-item:hover {
    border-color: var(--brand-secondary);
    box-shadow: var(--shadow-sm);
}

.faq-item.open {
    border-color: var(--brand-secondary);
    box-shadow: var(--shadow-md);
}

.faq-question {
    width: 100%;
    text-align: left;
    padding: 18px 22px;
    background-color: transparent;
    border: none;
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-dark-heading);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
    transition: var(--transition);
    font-family: inherit;
}

.faq-question:hover {
    background-color: rgba(30, 58, 95, 0.04);
}

body.dark-mode .faq-question:hover {
    background-color: #2d3748;
}

.faq-question .faq-icon {
    flex-shrink: 0;
    width: 22px;
    height: 22px;
    transition: transform 0.35s cubic-bezier(0.4, 0, 0.2, 1);
    fill: var(--brand-primary);
}

body.dark-mode .faq-question .faq-icon {
    fill: #93c5fd;
}

.faq-item.open .faq-question .faq-icon {
    transform: rotate(180deg);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.35s ease, padding 0.35s ease;
    padding: 0 22px;
    background-color: rgba(248, 250, 252, 0.6);
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.8;
}

body.dark-mode .faq-answer {
    background-color: rgba(15, 23, 42, 0.6);
    color: #e2e8f0;
}

.faq-item.open .faq-answer {
    max-height: 600px;
    padding: 0 22px 20px;
}

/* ============ HowTo 步骤 ============ */
.howto-steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 24px;
    counter-reset: step;
}

.step-card {
    background: var(--bg-glass);
    -webkit-backdrop-filter: blur(12px) saturate(160%);
    backdrop-filter: blur(12px) saturate(160%);
    border: 1px solid var(--bg-glass-border);
    border-radius: var(--radius);
    padding: 28px 22px;
    position: relative;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    overflow: hidden;
}

.step-card::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(30, 58, 95, 0.03) 0%, transparent 60%);
    opacity: 0;
    transition: opacity 0.4s ease;
    pointer-events: none;
}

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

.step-card:hover {
    box-shadow: var(--shadow-glow);
    transform: translateY(-5px);
    border-color: var(--brand-secondary);
}

.step-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background: var(--brand-gradient);
    color: #ffffff;
    font-weight: 800;
    font-size: 1.1rem;
    border-radius: 50%;
    margin-bottom: 16px;
    box-shadow: 0 4px 12px rgba(30, 58, 95, 0.25);
    transition: var(--transition-bounce);
}

.step-card:hover .step-number {
    transform: scale(1.12) rotate(-8deg);
}

body.dark-mode .step-number {
    background: linear-gradient(135deg, #3b82f6 0%, #60a5fa 100%);
}

.step-title {
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--text-dark-heading);
    margin-bottom: 8px;
}

.step-desc {
    font-size: 0.93rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* ============ 联系我们 ============ */
.contact-section {
    background: var(--bg-glass);
    -webkit-backdrop-filter: blur(12px);
    backdrop-filter: blur(12px);
    border-top: 1px solid var(--border-light);
}

.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 48px;
}

.contact-info h3 {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--text-dark-heading);
    margin-bottom: 20px;
}

.contact-info p {
    font-size: 0.98rem;
    color: var(--text-secondary);
    margin-bottom: 12px;
    line-height: 1.7;
}

.contact-info strong {
    color: var(--text-dark-heading);
    font-weight: 600;
}

.contact-form {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.form-group label {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-secondary);
}

.form-group input,
.form-group textarea {
    padding: 12px 16px;
    border: 1px solid var(--border-light);
    border-radius: var(--radius-sm);
    font-size: 0.95rem;
    font-family: inherit;
    background-color: var(--bg-card);
    color: var(--text-primary);
    transition: var(--transition);
    outline: none;
}

.form-group input:focus,
.form-group textarea:focus {
    border-color: var(--brand-secondary);
    box-shadow: 0 0 0 3px rgba(44, 82, 130, 0.15);
    transform: translateY(-2px);
}

.form-group textarea {
    resize: vertical;
    min-height: 100px;
}

.form-group input::placeholder,
.form-group textarea::placeholder {
    color: var(--text-light);
}

/* ============ 页脚 ============ */
.footer {
    background: linear-gradient(180deg, #0f172a 0%, #0b1120 100%);
    color: #cbd5e1;
    padding: 56px 0 24px;
    transition: background 0.35s ease;
    position: relative;
    overflow: hidden;
}

.footer::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(90deg, transparent, rgba(59, 130, 246, 0.4), transparent);
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 40px;
    margin-bottom: 40px;
}

.footer-col h4 {
    color: #f1f5f9;
    font-size: 1rem;
    font-weight: 700;
    margin-bottom: 16px;
    position: relative;
    padding-bottom: 10px;
}

.footer-col h4::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 0;
    width: 28px;
    height: 2px;
    background: var(--brand-accent);
    border-radius: 2px;
}

.footer-col p {
    font-size: 0.9rem;
    line-height: 1.8;
    color: #cbd5e1;
    margin-bottom: 10px;
}

.footer-col ul {
    list-style: none;
    padding: 0;
}

.footer-col li {
    margin-bottom: 8px;
}

.footer-col a {
    color: #93c5fd;
    text-decoration: none;
    font-size: 0.9rem;
    transition: var(--transition);
    display: inline-block;
}

.footer-col a:hover {
    color: #ffffff;
    transform: translateX(4px);
}

.footer-bottom {
    border-top: 1px solid #1e293b;
    padding-top: 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 12px;
    font-size: 0.85rem;
    color: #94a3b8;
}

.footer-bottom a {
    color: #93c5fd;
    text-decoration: none;
    transition: var(--transition);
}

.footer-bottom a:hover {
    color: #ffffff;
    text-decoration: underline;
}

/* ============ 返回顶部 ============ */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--brand-gradient);
    color: #ffffff;
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px) scale(0.9);
    transition: var(--transition-bounce);
    z-index: 900;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0) scale(1);
}

.back-to-top:hover {
    transform: translateY(-5px) scale(1.08);
    box-shadow: var(--shadow-glow);
}

.back-to-top svg {
    width: 22px;
    height: 22px;
    fill: currentColor;
}

/* ============ 滚动动画 ============ */
.reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.7s cubic-bezier(0.4, 0, 0.2, 1), transform 0.7s cubic-bezier(0.4, 0, 0.2, 1);
}

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

/* ============ 响应式 ============ */
@media (max-width: 1024px) {
    .hero-inner {
        grid-template-columns: 1fr;
        text-align: center;
    }
    .hero-actions {
        justify-content: center;
    }
    .hero-visual {
        order: -1;
    }
    .about-grid {
        grid-template-columns: 1fr;
    }
    .contact-grid {
        grid-template-columns: 1fr;
    }
    .footer-grid {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 768px) {
    .nav-menu {
        display: none;
    }
    .mobile-toggle {
        display: block;
    }
    .search-box {
        display: none;
    }
    .hero-title {
        font-size: 1.9rem;
    }
    .hero-subtitle {
        font-size: 1rem;
    }
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    .section {
        padding: 44px 0;
    }
    .section-title {
        font-size: 1.6rem;
    }
    .footer-grid {
        grid-template-columns: 1fr;
        gap: 28px;
    }
    .footer-bottom {
        flex-direction: column;
        text-align: center;
    }
    .back-to-top {
        bottom: 20px;
        right: 20px;
        width: 42px;
        height: 42px;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 1.6rem;
    }
    .stats-grid {
        grid-template-columns: 1fr 1fr;
        gap: 12px;
    }
    .stat-number {
        font-size: 1.6rem;
    }
    .card-grid {
        grid-template-columns: 1fr;
    }
    .article-list {
        grid-template-columns: 1fr;
    }
    .howto-steps {
        grid-template-columns: 1fr;
    }
    .btn {
        padding: 10px 22px;
        font-size: 0.95rem;
    }
}

/* ============ 无障碍与打印 ============ */
@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;
    }
}

::selection {
    background: rgba(44, 82, 130, 0.2);
    color: var(--brand-primary);
}

body.dark-mode ::selection {
    background: rgba(59, 130, 246, 0.3);
    color: #ffffff;
}

::-webkit-scrollbar {
    width: 10px;
    height: 10px;
}

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

::-webkit-scrollbar-thumb {
    background: linear-gradient(180deg, #94a3b8 0%, #64748b 100%);
    border-radius: 5px;
    border: 2px solid var(--bg-body);
}

::-webkit-scrollbar-thumb:hover {
    background: linear-gradient(180deg, #64748b 0%, #475569 100%);
}

:focus-visible {
    outline: 2px solid var(--brand-accent);
    outline-offset: 2px;
    border-radius: 4px;
}