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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", sans-serif;
    line-height: 1.7;
    color: #1e2a3a;
    background: #f9fbfd;
    transition: background 0.3s ease, color 0.3s ease;
}

a {
    color: #1e6bb8;
    text-decoration: none;
    transition: color 0.2s;
}

a:hover {
    text-decoration: underline;
    color: #2b6c9e;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* 导航吸顶 + 毛玻璃 */
.navbar {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid rgba(230, 237, 244, 0.7);
    transition: background 0.3s, border-color 0.3s;
}

.navbar .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: #1e2a3a;
    letter-spacing: 1px;
    transition: color 0.3s;
}

.logo span {
    color: #2b6c9e;
}

.nav-links {
    display: flex;
    gap: 28px;
    list-style: none;
    align-items: center;
}

.nav-links a {
    font-size: 0.95rem;
    color: #2c3e50;
    font-weight: 500;
    position: relative;
    transition: color 0.2s;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: #2b6c9e;
    transition: width 0.3s ease;
}

.nav-links a:hover {
    color: #1e6bb8;
    text-decoration: none;
}

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

.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    background: none;
    border: none;
    padding: 8px;
}

.menu-toggle span {
    width: 26px;
    height: 2px;
    background: #1e2a3a;
    border-radius: 2px;
    transition: background 0.3s;
}

/* 渐变Banner */
.banner {
    background: linear-gradient(135deg, #e3f0fa 0%, #c5dff0 50%, #a8cce0 100%);
    padding: 60px 0 80px;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.banner::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle at 30% 50%, rgba(43, 108, 158, 0.08) 0%, transparent 50%),
                radial-gradient(circle at 70% 50%, rgba(43, 108, 158, 0.06) 0%, transparent 50%);
    animation: bannerShift 12s ease-in-out infinite alternate;
}

@keyframes bannerShift {
    0% { transform: translate(0, 0) rotate(0deg); }
    100% { transform: translate(2%, 2%) rotate(3deg); }
}

.banner .container {
    position: relative;
    z-index: 1;
}

.banner h1 {
    font-size: 2.6rem;
    font-weight: 700;
    color: #1a2a3a;
    margin-bottom: 16px;
    text-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

.banner p {
    font-size: 1.2rem;
    color: #2c4a6a;
    max-width: 720px;
    margin: 0 auto 24px;
    line-height: 1.8;
}

.banner .btn {
    display: inline-block;
    background: #2b6c9e;
    color: #fff;
    padding: 14px 40px;
    border-radius: 40px;
    font-weight: 600;
    font-size: 1rem;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(43, 108, 158, 0.3);
}

.banner .btn:hover {
    background: #1f5a85;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(43, 108, 158, 0.4);
    text-decoration: none;
}

/* 通用section */
section {
    padding: 64px 0;
}

.section-title {
    font-size: 2rem;
    font-weight: 700;
    color: #1e2a3a;
    margin-bottom: 12px;
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 60px;
    height: 3px;
    background: linear-gradient(90deg, #2b6c9e, #5a9bc7);
    border-radius: 2px;
}

.section-subtitle {
    font-size: 1rem;
    color: #5a6e7e;
    margin-bottom: 40px;
}

/* 网格布局 */
.grid-2 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
}

.grid-3 {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 32px;
}

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

/* 圆角卡片 + hover动画 */
.card {
    background: #fff;
    border-radius: 16px;
    padding: 28px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.03);
    border: 1px solid #eef3f8;
    transition: transform 0.3s ease, box-shadow 0.3s ease, background 0.3s, border-color 0.3s;
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 3px;
    background: linear-gradient(90deg, #2b6c9e, #5a9bc7);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.3s ease;
}

.card:hover {
    transform: translateY(-6px);
    box-shadow: 0 12px 28px rgba(43, 108, 158, 0.1);
    border-color: #c5dff0;
}

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

.card h3 {
    font-size: 1.3rem;
    margin-bottom: 12px;
    color: #1e2a3a;
}

.card p {
    color: #3d5166;
    line-height: 1.8;
}

.icon-svg {
    width: 48px;
    height: 48px;
    margin-bottom: 16px;
    fill: #2b6c9e;
    transition: transform 0.3s ease;
}

.card:hover .icon-svg {
    transform: scale(1.1);
}

/* 文章列表 */
.article-list {
    list-style: none;
}

.article-list li {
    padding: 16px 0;
    border-bottom: 1px solid #e6edf4;
    transition: padding-left 0.3s ease;
}

.article-list li:hover {
    padding-left: 8px;
    border-bottom-color: #c5dff0;
}

.article-list li:last-child {
    border: none;
}

.article-meta {
    font-size: 0.85rem;
    color: #7a8a9a;
}

.article-list h4 {
    font-size: 1.1rem;
    margin: 4px 0 6px;
    transition: color 0.2s;
}

.article-list li:hover h4 {
    color: #2b6c9e;
}

.article-list p {
    color: #3d5166;
}

.read-more {
    color: #1e6bb8;
    font-weight: 500;
    display: inline-block;
    transition: transform 0.2s;
}

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

/* FAQ */
.faq-item {
    border-bottom: 1px solid #e6edf4;
    padding: 16px 0;
    transition: background 0.2s;
}

.faq-item:hover {
    background: rgba(43, 108, 158, 0.02);
}

.faq-question {
    font-weight: 600;
    font-size: 1.05rem;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: color 0.2s;
}

.faq-question:hover {
    color: #2b6c9e;
}

.faq-question::after {
    content: "+";
    font-size: 1.4rem;
    color: #2b6c9e;
    transition: transform 0.3s ease;
}

.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;
    color: #3d5166;
    margin-top: 0;
    padding: 0 16px;
}

.faq-item.open .faq-answer {
    max-height: 600px;
    margin-top: 8px;
    padding: 8px 16px;
}

/* HowTo */
.howto-step {
    margin-bottom: 24px;
    padding: 16px 20px;
    border-radius: 12px;
    background: rgba(255, 255, 255, 0.5);
    border: 1px solid #eef3f8;
    transition: background 0.3s, border-color 0.3s;
}

.howto-step:hover {
    background: #fff;
    border-color: #c5dff0;
}

.howto-step h4 {
    font-size: 1.1rem;
    color: #1e2a3a;
    margin-bottom: 8px;
}

.howto-step p {
    color: #3d5166;
}

/* 面包屑 */
.breadcrumb {
    padding: 16px 0;
    font-size: 0.9rem;
    color: #6a7a8a;
}

.breadcrumb a {
    color: #1e6bb8;
}

.breadcrumb a:hover {
    color: #2b6c9e;
}

/* 页脚 */
.footer {
    background: #1e2a3a;
    color: #d0dce8;
    padding: 48px 0 24px;
    transition: background 0.3s;
}

.footer a {
    color: #b0c8dd;
    transition: color 0.2s;
}

.footer a:hover {
    color: #fff;
    text-decoration: none;
}

.footer .grid-4 {
    gap: 32px;
}

.footer h4 {
    color: #fff;
    margin-bottom: 16px;
    font-size: 1.1rem;
    position: relative;
    display: inline-block;
}

.footer h4::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 30px;
    height: 2px;
    background: #2b6c9e;
}

.footer ul {
    list-style: none;
}

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

.footer-bottom {
    border-top: 1px solid #2c4054;
    margin-top: 32px;
    padding-top: 24px;
    text-align: center;
    font-size: 0.85rem;
}

/* 返回顶部 */
.back-to-top {
    position: fixed;
    bottom: 40px;
    right: 40px;
    width: 48px;
    height: 48px;
    background: #2b6c9e;
    color: #fff;
    border: none;
    border-radius: 50%;
    font-size: 1.5rem;
    cursor: pointer;
    display: none;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    z-index: 999;
    transition: all 0.3s ease;
}

.back-to-top.visible {
    display: flex;
}

.back-to-top:hover {
    background: #1f5a85;
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(43, 108, 158, 0.3);
}

/* 站内搜索 */
.search-box {
    display: flex;
    gap: 8px;
    margin: 16px 0;
}

.search-box input {
    flex: 1;
    padding: 10px 16px;
    border: 1px solid #d0dce8;
    border-radius: 40px;
    font-size: 1rem;
    transition: border-color 0.3s, box-shadow 0.3s;
}

.search-box input:focus {
    outline: none;
    border-color: #2b6c9e;
    box-shadow: 0 0 0 3px rgba(43, 108, 158, 0.1);
}

.search-box button {
    padding: 10px 20px;
    background: #2b6c9e;
    color: #fff;
    border: none;
    border-radius: 40px;
    cursor: pointer;
    transition: background 0.2s, transform 0.2s;
}

.search-box button:hover {
    background: #1f5a85;
    transform: translateY(-1px);
}

/* 暗黑模式切换按钮 */
.dark-mode-toggle {
    background: none;
    border: 1px solid #c5dff0;
    border-radius: 40px;
    padding: 6px 14px;
    font-size: 0.9rem;
    cursor: pointer;
    color: #1e2a3a;
    transition: all 0.3s ease;
}

.dark-mode-toggle:hover {
    background: rgba(43, 108, 158, 0.1);
    border-color: #2b6c9e;
}

/* 暗黑模式 */
body.dark {
    background: #121a24;
    color: #dce6f0;
}

body.dark .navbar {
    background: rgba(26, 37, 53, 0.85);
    border-color: rgba(44, 64, 84, 0.7);
}

body.dark .card {
    background: #1f2c3c;
    border-color: #2c4054;
}

body.dark .card:hover {
    border-color: #3d5a6e;
    box-shadow: 0 12px 28px rgba(0,0,0,0.3);
}

body.dark .banner {
    background: linear-gradient(135deg, #1f2c3c 0%, #2a3a4e 50%, #1a2535 100%);
}

body.dark .banner h1 {
    color: #e0ecf5;
}

body.dark .banner p {
    color: #b0c8dd;
}

body.dark .banner .btn {
    background: #3d7aaf;
}

body.dark .banner .btn:hover {
    background: #2b6c9e;
}

body.dark .footer {
    background: #0e1620;
}

body.dark .logo {
    color: #e0ecf5;
}

body.dark .nav-links a {
    color: #c0d4e4;
}

body.dark .nav-links a::after {
    background: #5a9bc7;
}

body.dark .nav-links a:hover {
    color: #5a9bc7;
}

body.dark .menu-toggle span {
    background: #dce6f0;
}

body.dark .dark-mode-toggle {
    border-color: #3d5a6e;
    color: #dce6f0;
}

body.dark .dark-mode-toggle:hover {
    background: rgba(90, 155, 199, 0.15);
    border-color: #5a9bc7;
}

body.dark .faq-question {
    color: #dce6f0;
}

body.dark .faq-item:hover {
    background: rgba(90, 155, 199, 0.05);
}

body.dark .section-title {
    color: #e0ecf5;
}

body.dark .section-subtitle {
    color: #9ab0c4;
}

body.dark .article-meta {
    color: #8aa0b4;
}

body.dark .breadcrumb {
    color: #8aa0b4;
}

body.dark .breadcrumb a {
    color: #5a9bc7;
}

body.dark .howto-step {
    background: rgba(31, 44, 60, 0.5);
    border-color: #2c4054;
}

body.dark .howto-step:hover {
    background: #1f2c3c;
    border-color: #3d5a6e;
}

body.dark .article-list li {
    border-bottom-color: #2c4054;
}

body.dark .article-list li:hover {
    border-bottom-color: #3d5a6e;
}

body.dark .search-box input {
    background: #1f2c3c;
    border-color: #2c4054;
    color: #dce6f0;
}

body.dark .search-box input:focus {
    border-color: #5a9bc7;
}

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

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

/* 数字动画占位 */
.stat-number {
    font-size: 2.2rem;
    font-weight: 700;
    color: #2b6c9e;
    transition: color 0.3s;
}

/* 响应式布局 */
@media (max-width: 1024px) {
    .grid-4 {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
        flex-direction: column;
        background: rgba(255, 255, 255, 0.98);
        backdrop-filter: blur(12px);
        -webkit-backdrop-filter: blur(12px);
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        padding: 20px 24px;
        border-bottom: 1px solid #e6edf4;
        box-shadow: 0 8px 20px rgba(0,0,0,0.05);
    }

    body.dark .nav-links {
        background: rgba(26, 37, 53, 0.98);
        border-bottom-color: #2c4054;
    }

    .nav-links.open {
        display: flex;
    }

    .menu-toggle {
        display: flex;
    }

    .grid-2, .grid-3, .grid-4 {
        grid-template-columns: 1fr;
    }

    .banner h1 {
        font-size: 1.8rem;
    }

    .banner p {
        font-size: 1rem;
    }

    .banner {
        padding: 40px 0 60px;
    }

    section {
        padding: 40px 0;
    }

    .section-title {
        font-size: 1.6rem;
    }

    .back-to-top {
        bottom: 20px;
        right: 20px;
        width: 40px;
        height: 40px;
        font-size: 1.2rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 16px;
    }

    .banner h1 {
        font-size: 1.5rem;
    }

    .banner .btn {
        padding: 12px 30px;
        font-size: 0.9rem;
    }

    .card {
        padding: 20px;
    }

    .footer .grid-4 {
        gap: 24px;
    }
}