/* 全局重置与基础 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    background: #f5f7fa;
    color: #2d3748;
    line-height: 1.8;
    font-size: 16px;
    transition: background 0.3s, color 0.3s;
}

a {
    color: #1a5a8a;
    text-decoration: none;
    transition: color 0.2s;
}

a:hover {
    color: #0d3b5c;
}

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

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

/* 导航 */
.header {
    background: #1a3a5c;
    color: #fff;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    transition: box-shadow 0.3s;
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 20px;
    max-width: 1200px;
    margin: 0 auto;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo svg {
    height: 40px;
}

.nav {
    display: flex;
    gap: 24px;
}

.nav a {
    color: #d0e0f0;
    font-size: 15px;
    padding: 6px 0;
    border-bottom: 2px solid transparent;
    transition: border-color 0.2s, color 0.2s;
}

.nav a:hover,
.nav a.active {
    color: #fff;
    border-bottom-color: #4a9eff;
}

.menu-toggle {
    display: none;
    background: none;
    border: none;
    color: #fff;
    font-size: 28px;
    cursor: pointer;
}

.search-box {
    display: flex;
    align-items: center;
    gap: 6px;
}

.search-box input {
    padding: 6px 12px;
    border: none;
    border-radius: 20px;
    font-size: 14px;
    width: 160px;
    background: #2a4a6c;
    color: #fff;
    transition: background 0.3s, width 0.3s;
}

.search-box input::placeholder {
    color: #8ab4d6;
}

.search-box input:focus {
    outline: none;
    background: #3a5a7c;
    width: 200px;
}

.search-box button {
    background: none;
    border: none;
    color: #fff;
    cursor: pointer;
    font-size: 18px;
    transition: transform 0.2s;
}

.search-box button:hover {
    transform: scale(1.1);
}

@media (max-width: 768px) {
    .nav {
        display: none;
        flex-direction: column;
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        background: #1a3a5c;
        padding: 20px;
        gap: 12px;
        box-shadow: 0 4px 12px rgba(0,0,0,0.2);
    }
    .nav.open {
        display: flex;
    }
    .menu-toggle {
        display: block;
    }
    .search-box input {
        width: 120px;
    }
}

/* 面包屑 */
.breadcrumb {
    background: #eef2f7;
    padding: 12px 0;
    font-size: 14px;
    color: #5a6a7a;
}

.breadcrumb a {
    color: #1a5a8a;
}

.breadcrumb span {
    margin: 0 6px;
}

/* Banner - 渐变背景 */
.banner {
    position: relative;
    overflow: hidden;
    min-height: 420px;
    background: linear-gradient(135deg, #1a3a5c 0%, #2a5a8c 40%, #3a7abc 100%);
    display: flex;
    align-items: center;
}

.banner::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle at 30% 40%, rgba(74, 158, 255, 0.15) 0%, transparent 50%),
                radial-gradient(circle at 70% 60%, rgba(255, 255, 255, 0.05) 0%, transparent 50%);
    animation: bannerGlow 10s ease-in-out infinite alternate;
}

@keyframes bannerGlow {
    0% { transform: translate(0, 0); }
    100% { transform: translate(20px, -20px); }
}

.banner-slide {
    display: none;
    padding: 60px 20px;
    text-align: center;
    color: #fff;
    position: relative;
    z-index: 1;
}

.banner-slide.active {
    display: block;
    animation: fadeIn 0.6s ease;
}

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

.banner h1 {
    font-size: 36px;
    margin-bottom: 16px;
    font-weight: 700;
    text-shadow: 0 2px 10px rgba(0,0,0,0.2);
}

.banner p {
    font-size: 18px;
    max-width: 700px;
    margin: 0 auto 24px;
    opacity: 0.9;
}

.banner .btn {
    display: inline-block;
    padding: 12px 32px;
    background: linear-gradient(135deg, #4a9eff, #2a7acc);
    color: #fff;
    border-radius: 30px;
    font-size: 16px;
    font-weight: 600;
    transition: transform 0.2s, box-shadow 0.2s;
    box-shadow: 0 4px 15px rgba(74, 158, 255, 0.4);
}

.banner .btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(74, 158, 255, 0.6);
}

.banner-dots {
    position: absolute;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 10px;
    z-index: 2;
}

.banner-dots span {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: rgba(255,255,255,0.4);
    cursor: pointer;
    transition: background 0.3s, transform 0.2s;
}

.banner-dots span.active {
    background: #fff;
    transform: scale(1.2);
}

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

.section-title {
    text-align: center;
    font-size: 28px;
    font-weight: 700;
    color: #1a3a5c;
    margin-bottom: 12px;
}

.section-subtitle {
    text-align: center;
    color: #5a7a9a;
    font-size: 16px;
    margin-bottom: 40px;
}

.grid-2 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
}

.grid-3 {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 24px;
}

.grid-4 {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr 1fr;
    gap: 20px;
}

@media (max-width: 768px) {
    .grid-2, .grid-3, .grid-4 {
        grid-template-columns: 1fr;
    }
}

/* 圆角卡片 + 毛玻璃效果 */
.card {
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-radius: 16px;
    padding: 24px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.06);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border: 1px solid rgba(255,255,255,0.3);
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 30px rgba(0,0,0,0.12);
}

.card h3 {
    font-size: 18px;
    margin-bottom: 10px;
    color: #1a3a5c;
}

.card p {
    color: #4a5a6a;
    font-size: 15px;
}

.card .meta {
    font-size: 13px;
    color: #8a9aaa;
    margin-top: 12px;
}

/* 数字动画 */
.stats {
    background: linear-gradient(135deg, #1a3a5c, #2a4a6c);
    color: #fff;
    text-align: center;
    padding: 40px 0;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
}

.stat-item {
    padding: 20px;
}

.stat-number {
    font-size: 40px;
    font-weight: 700;
}

.stat-label {
    font-size: 16px;
    opacity: 0.8;
    margin-top: 6px;
}

@media (max-width: 768px) {
    .stats-grid {
        grid-template-columns: 1fr 1fr;
    }
}

/* FAQ */
.faq-item {
    border-bottom: 1px solid #e2e8f0;
    padding: 16px 0;
    cursor: pointer;
    transition: background 0.2s;
}

.faq-item:hover {
    background: rgba(74, 158, 255, 0.05);
}

.faq-question {
    font-weight: 600;
    font-size: 17px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.faq-question::after {
    content: '+';
    font-size: 22px;
    color: #4a9eff;
    transition: transform 0.3s;
}

.faq-item.open .faq-question::after {
    content: '−';
    transform: rotate(180deg);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease, padding 0.3s ease;
    padding: 0 16px 0 0;
    color: #4a5a6a;
    font-size: 15px;
    line-height: 1.7;
}

.faq-item.open .faq-answer {
    max-height: 500px;
    padding-top: 12px;
}

/* 文章列表 */
.article-list .card {
    padding: 20px;
}

.article-list .card h3 {
    font-size: 17px;
}

.article-list .card p {
    font-size: 14px;
}

.read-more {
    color: #4a9eff;
    font-weight: 600;
    font-size: 14px;
    transition: color 0.2s;
}

.read-more:hover {
    color: #1a5a8a;
}

/* 页脚 */
.footer {
    background: linear-gradient(135deg, #1a2a3c, #0e1a2a);
    color: #b0c4d8;
    padding: 48px 0 24px;
    font-size: 14px;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr 1fr;
    gap: 30px;
}

.footer h4 {
    color: #fff;
    font-size: 16px;
    margin-bottom: 12px;
}

.footer a {
    color: #8ab4d6;
    display: block;
    margin-bottom: 6px;
    transition: color 0.2s, padding-left 0.2s;
}

.footer a:hover {
    color: #fff;
    padding-left: 4px;
}

.footer-bottom {
    border-top: 1px solid #2a3a4c;
    margin-top: 32px;
    padding-top: 20px;
    text-align: center;
    color: #7a8a9a;
}

@media (max-width: 768px) {
    .footer-grid {
        grid-template-columns: 1fr 1fr;
    }
}

/* 返回顶部 */
.back-top {
    position: fixed;
    bottom: 40px;
    right: 30px;
    width: 48px;
    height: 48px;
    background: linear-gradient(135deg, #1a3a5c, #2a5a8c);
    color: #fff;
    border: none;
    border-radius: 50%;
    font-size: 22px;
    cursor: pointer;
    display: none;
    box-shadow: 0 4px 15px rgba(0,0,0,0.3);
    z-index: 999;
    transition: transform 0.2s, opacity 0.3s;
}

.back-top.show {
    display: block;
}

.back-top:hover {
    transform: translateY(-3px);
}

/* 暗黑模式 */
body.dark {
    background: #1a1a2e;
    color: #e0e0e0;
}

body.dark .card {
    background: rgba(42, 42, 62, 0.9);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-color: rgba(255,255,255,0.1);
    color: #e0e0e0;
}

body.dark .card h3 {
    color: #c0d0e0;
}

body.dark .card p {
    color: #b0b0c0;
}

body.dark .breadcrumb {
    background: #222;
}

body.dark .breadcrumb a {
    color: #6a9eff;
}

body.dark .footer {
    background: linear-gradient(135deg, #0e0e1a, #1a1a2e);
}

body.dark .section-title {
    color: #c0d0e0;
}

body.dark .section-subtitle {
    color: #8a9aaa;
}

body.dark .faq-item {
    border-color: #3a3a4e;
}

body.dark .faq-question {
    color: #d0d0e0;
}

body.dark .faq-answer {
    color: #b0b0c0;
}

body.dark .stats {
    background: linear-gradient(135deg, #0e0e1a, #1a1a2e);
}

body.dark .banner {
    background: linear-gradient(135deg, #0e0e1a, #1a2a3e, #2a3a4e);
}

body.dark .header {
    background: #0e0e1a;
}

body.dark .search-box input {
    background: #2a2a3e;
    color: #e0e0e0;
}

body.dark .search-box input:focus {
    background: #3a3a4e;
}

body.dark .faq-item:hover {
    background: rgba(74, 158, 255, 0.1);
}

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

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

/* 暗黑模式按钮 */
.dark-mode-btn {
    background: none;
    border: 2px solid rgba(255,255,255,0.3);
    color: #fff;
    padding: 4px 12px;
    border-radius: 20px;
    cursor: pointer;
    font-size: 14px;
    transition: border-color 0.2s, background 0.2s;
}

.dark-mode-btn:hover {
    border-color: #4a9eff;
    background: rgba(74, 158, 255, 0.1);
}

/* 响应式小调整 */
@media (max-width: 480px) {
    .banner h1 {
        font-size: 28px;
    }
    .banner p {
        font-size: 16px;
    }
    .section-title {
        font-size: 24px;
    }
    .stat-number {
        font-size: 32px;
    }
}