/* 全局重置与变量 */
:root {
    --primary: #1a1a2e;
    --accent: #e94560;
    --bg: #f5f5f5;
    --text: #222;
    --light: #fff;
    --gray: #666;
    --border: #ddd;
    --glass-bg: rgba(255, 255, 255, 0.15);
    --glass-border: rgba(255, 255, 255, 0.25);
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 6px 20px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 12px 40px rgba(0, 0, 0, 0.12);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Noto Sans SC", sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
    transition: background var(--transition), color var(--transition);
}

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

a:hover {
    text-decoration: underline;
    color: #d43f5a;
}

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

/* 导航吸顶 + 毛玻璃 */
.navbar {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--glass-border);
    padding: 12px 0;
    box-shadow: var(--shadow-sm);
    transition: background var(--transition), border-color var(--transition);
}

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

.navbar .logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--light);
    letter-spacing: 1px;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

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

.nav-links {
    display: flex;
    gap: 24px;
    list-style: none;
}

.nav-links a {
    color: var(--light);
    font-size: 0.95rem;
    padding: 6px 0;
    border-bottom: 2px solid transparent;
    transition: border-color var(--transition), color var(--transition);
    position: relative;
}

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

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

.nav-links a:hover {
    border-bottom-color: transparent;
    text-decoration: none;
    color: #ff7f8a;
}

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    color: var(--light);
    font-size: 1.8rem;
    cursor: pointer;
    transition: transform var(--transition);
}

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

@media (max-width: 768px) {
    .nav-links {
        display: none;
        flex-direction: column;
        width: 100%;
        margin-top: 12px;
        gap: 12px;
        background: var(--glass-bg);
        backdrop-filter: blur(12px);
        -webkit-backdrop-filter: blur(12px);
        border-radius: var(--radius-md);
        padding: 16px;
    }
    .nav-links.active {
        display: flex;
    }
    .mobile-menu-btn {
        display: block;
    }
}

/* 面包屑 */
.breadcrumb {
    background: var(--light);
    padding: 10px 0;
    border-bottom: 1px solid var(--border);
    font-size: 0.9rem;
    transition: background var(--transition), border-color var(--transition);
}

.breadcrumb a {
    color: var(--gray);
}

.breadcrumb span {
    color: var(--text);
}

/* 通用区块 */
section {
    padding: 50px 0;
}

.section-title {
    font-size: 1.8rem;
    margin-bottom: 30px;
    text-align: center;
    color: var(--primary);
    position: relative;
    transition: color var(--transition);
}

.section-title:after {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background: var(--accent);
    margin: 12px auto 0;
    border-radius: 2px;
}

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

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

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

/* 卡片 - 毛玻璃+圆角+悬浮动画 */
.card {
    background: var(--light);
    border-radius: var(--radius-md);
    padding: 24px;
    box-shadow: var(--shadow-sm);
    transition: transform var(--transition), box-shadow var(--transition), background var(--transition);
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle at 30% 50%, rgba(233, 69, 96, 0.03), transparent 60%);
    opacity: 0;
    transition: opacity var(--transition);
    pointer-events: none;
}

.card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-md);
}

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

.btn {
    display: inline-block;
    background: var(--accent);
    color: var(--light);
    padding: 10px 24px;
    border-radius: 6px;
    font-weight: 600;
    transition: background var(--transition), transform var(--transition), box-shadow var(--transition);
    box-shadow: 0 4px 12px rgba(233, 69, 96, 0.3);
}

.btn:hover {
    background: #c73e54;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(233, 69, 96, 0.4);
    text-decoration: none;
}

/* Banner - 渐变背景 */
.banner {
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 40%, #0f3460 70%, #e94560 100%);
    color: var(--light);
    padding: 60px 0;
    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 70% 30%, rgba(233, 69, 96, 0.15), transparent 50%);
    animation: bannerGlow 6s ease-in-out infinite alternate;
}

@keyframes bannerGlow {
    0% {
        transform: translate(0, 0) scale(1);
    }
    100% {
        transform: translate(10%, 10%) scale(1.1);
    }
}

.banner h1 {
    font-size: 2.6rem;
    margin-bottom: 16px;
    position: relative;
    z-index: 1;
    text-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
}

.banner p {
    font-size: 1.2rem;
    max-width: 700px;
    margin: 0 auto 24px;
    color: #ccc;
    position: relative;
    z-index: 1;
}

.banner .btn {
    font-size: 1.1rem;
    position: relative;
    z-index: 1;
}

/* 文章列表 */
.article-item {
    border-bottom: 1px solid var(--border);
    padding: 18px 0;
    transition: padding-left var(--transition), background var(--transition);
    border-radius: var(--radius-sm);
}

.article-item:last-child {
    border-bottom: none;
}

.article-item:hover {
    padding-left: 12px;
    background: rgba(233, 69, 96, 0.03);
}

.article-item h4 {
    font-size: 1.15rem;
}

.article-item .meta {
    color: var(--gray);
    font-size: 0.85rem;
    margin: 4px 0 8px;
}

.article-item p {
    color: #444;
    transition: color var(--transition);
}

/* FAQ */
.faq-item {
    border-bottom: 1px solid var(--border);
    padding: 16px 0;
    cursor: pointer;
    transition: background var(--transition), padding var(--transition);
    border-radius: var(--radius-sm);
}

.faq-item:hover {
    background: rgba(233, 69, 96, 0.02);
    padding-left: 8px;
}

.faq-question {
    font-weight: 600;
    font-size: 1.05rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: color var(--transition);
}

.faq-question span {
    transition: transform var(--transition);
    font-size: 1.2rem;
}

.faq-item.active .faq-question span {
    transform: rotate(180deg);
}

.faq-answer {
    margin-top: 12px;
    color: #444;
    display: none;
    transition: all var(--transition);
}

.faq-item.active .faq-answer {
    display: block;
    animation: fadeSlideIn 0.3s ease-out;
}

@keyframes fadeSlideIn {
    from {
        opacity: 0;
        transform: translateY(-8px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* 页脚 */
footer {
    background: var(--primary);
    color: #aaa;
    padding: 40px 0;
    font-size: 0.9rem;
    transition: background var(--transition);
}

footer a {
    color: #ccc;
    transition: color var(--transition);
}

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

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

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

footer h4 {
    color: var(--light);
    margin-bottom: 12px;
    position: relative;
    display: inline-block;
}

footer h4::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 24px;
    height: 2px;
    background: var(--accent);
    border-radius: 1px;
}

footer ul {
    list-style: none;
}

footer ul li {
    margin-bottom: 6px;
    transition: transform var(--transition);
}

footer ul li:hover {
    transform: translateX(4px);
}

.copyright {
    text-align: center;
    padding-top: 24px;
    border-top: 1px solid #333;
    margin-top: 24px;
    grid-column: 1 / -1;
}

/* 返回顶部 */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    background: var(--accent);
    color: var(--light);
    width: 44px;
    height: 44px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition), visibility var(--transition), transform var(--transition), background var(--transition);
    z-index: 999;
    border: none;
    box-shadow: 0 4px 16px rgba(233, 69, 96, 0.4);
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    background: #c73e54;
    transform: translateY(-4px) scale(1.05);
}

/* 暗黑模式 */
.dark-mode-toggle {
    background: none;
    border: 1px solid var(--light);
    color: var(--light);
    padding: 6px 14px;
    border-radius: 20px;
    cursor: pointer;
    font-size: 0.85rem;
    transition: background var(--transition), border-color var(--transition), transform var(--transition);
}

.dark-mode-toggle:hover {
    background: rgba(255, 255, 255, 0.1);
    transform: scale(1.05);
}

body.dark {
    --bg: #121212;
    --text: #e0e0e0;
    --light: #1e1e1e;
    --border: #333;
    --glass-bg: rgba(30, 30, 30, 0.8);
    --glass-border: rgba(255, 255, 255, 0.1);
    background: var(--bg);
    color: var(--text);
}

body.dark .card {
    background: #2a2a2a;
}

body.dark .card::before {
    background: radial-gradient(circle at 30% 50%, rgba(233, 69, 96, 0.06), transparent 60%);
}

body.dark .breadcrumb {
    background: #1e1e1e;
}

body.dark .banner {
    background: linear-gradient(135deg, #0a0a1a 0%, #12122a 40%, #1a1a3e 70%, #b33a4e 100%);
}

body.dark .article-item p {
    color: #aaa;
}

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

body.dark .section-title {
    color: #e0e0e0;
}

/* 滚动动画 */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

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

/* SVG 图片占位 */
.svg-placeholder {
    width: 100%;
    max-width: 300px;
    height: auto;
    display: block;
    margin: 0 auto;
    background: #eee;
    border-radius: var(--radius-sm);
    transition: background var(--transition);
}

body.dark .svg-placeholder {
    background: #333;
}

/* 附加微交互 */
::selection {
    background: var(--accent);
    color: var(--light);
}

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

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

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

::-webkit-scrollbar-thumb:hover {
    background: #c73e54;
}