/* =============================================
   科普知识网 - 前台样式（基于 Bootstrap 3.4.1）
   ============================================= */

:root {
    --primary: #4F46E5;
    --primary-dark: #3730A3;
    --primary-light: #EEF2FF;
    --accent: #F59E0B;
    --success: #10B981;
    --danger: #EF4444;
    --text: #1F2937;
    --text-light: #6B7280;
    --text-lighter: #9CA3AF;
    --bg: #F9FAFB;
    --bg-white: #FFFFFF;
    --border: #E5E7EB;
    --shadow: 0 1px 3px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.07);
    --shadow-lg: 0 10px 25px rgba(0,0,0,0.08);
    --radius: 12px;
    --radius-sm: 8px;
    --transition: all 0.2s ease;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    background: var(--bg);
    color: var(--text);
}

a { transition: var(--transition); }
a:hover { color: var(--primary-dark); }

.site-main { padding-top: 20px; }

/* ========== 顶部导航栏 ========== */
.site-navbar {
    background: var(--bg-white) !important;
    border-bottom: 1px solid var(--border) !important;
    box-shadow: var(--shadow);
    margin-bottom: 0;
    min-height: auto;
}
.site-navbar .navbar-brand {
    font-size: 20px;
    font-weight: 700;
    color: var(--text) !important;
    padding: 14px 15px;
}
.site-navbar .navbar-brand:hover { color: var(--primary) !important; }
.site-navbar .navbar-brand .brand-icon { font-size: 22px; margin-right: 4px; }

.site-navbar .navbar-nav > li > a {
    padding: 14px 13px;
    font-size: 14px;
    color: var(--text-light) !important;
    border-radius: 20px;
    margin: 4px 1px;
}
.site-navbar .navbar-nav > li > a:hover,
.site-navbar .navbar-nav > .active > a {
    background: var(--primary-light) !important;
    color: var(--primary) !important;
    font-weight: 500;
}

/* 导航栏搜索框 */
.site-navbar .navbar-form {
    padding-top: 7px;
    padding-bottom: 7px;
    margin-right: 0;
}
.site-navbar .navbar-form .input-group {
    max-width: 260px;
}
.site-navbar .navbar-form .form-control {
    border-radius: 20px 0 0 20px;
    border-color: var(--border);
    box-shadow: none;
}
.site-navbar .navbar-form .btn {
    border-radius: 0 20px 20px 0;
    border-color: var(--border);
    background: var(--primary);
    color: #fff;
    border-color: var(--primary);
}
.site-navbar .navbar-form .btn:hover {
    background: var(--primary-dark);
    border-color: var(--primary-dark);
}

/* 移动端汉堡按钮 */
.site-navbar .navbar-toggle { border-color: var(--border); margin-top: 10px; }
.site-navbar .navbar-toggle:hover, 
.site-navbar .navbar-toggle:focus { background: var(--primary-light); }
.site-navbar .navbar-toggle .icon-bar { background: var(--text-light); }

/* ========== 轮播广告区域 ========== */
.hero-section {
    margin: -20px -15px 30px;
    position: relative;
}
.hero-slider {
    overflow: hidden;
    min-height: 280px;
}
.hero-slide {
    padding: 60px 50px;
    color: #fff;
    display: none;
    min-height: 280px;
    animation: fadeIn 0.5s ease;
}
@keyframes fadeIn {
    from { opacity: 0.6; }
    to   { opacity: 1; }
}
.hero-slide.active { display: flex; align-items: center; }
.hero-content { max-width: 650px; padding: 0 15px; }
.hero-content h2 {
    font-size: 32px;
    margin-bottom: 14px;
    text-shadow: 0 2px 4px rgba(0,0,0,0.2);
}
.hero-content p {
    font-size: 16px;
    opacity: 0.95;
    margin-bottom: 20px;
    line-height: 1.7;
    text-shadow: 0 1px 2px rgba(0,0,0,0.15);
}
.hero-btn {
    display: inline-block;
    padding: 10px 28px;
    background: rgba(255,255,255,0.2);
    color: #fff !important;
    border: 2px solid rgba(255,255,255,0.6);
    border-radius: 24px;
    font-size: 15px;
    font-weight: 500;
    transition: all 0.3s;
}
.hero-btn:hover {
    background: #fff;
    color: var(--text) !important;
    border-color: #fff;
    text-decoration: none;
}
.hero-dots {
    position: absolute;
    bottom: 18px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 8px;
    z-index: 10;
}
.hero-dot {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: rgba(255,255,255,0.4);
    cursor: pointer;
    transition: all 0.3s;
}
.hero-dot.active, .hero-dot:hover {
    background: #fff;
    transform: scale(1.3);
}

/* ========== 分类卡片 ========== */
.category-cards { margin-bottom: 40px; }
.section-header {
    margin-bottom: 24px;
}
.section-header.text-center { text-align: center; }
.section-header h3 { font-size: 24px; margin-bottom: 8px; margin-top: 0; }
.section-header p { color: var(--text-light); }
.section-block { margin-bottom: 30px; }
.section-block .section-header { text-align: left; }

.category-card {
    background: var(--bg-white);
    border-radius: var(--radius);
    padding: 24px 20px;
    text-align: center;
    border: 1px solid var(--border);
    transition: var(--transition);
    display: block;
    color: var(--text);
    margin-bottom: 20px;
}
.category-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
    color: var(--text);
    text-decoration: none;
}
.category-card .card-icon { font-size: 36px; display: block; margin-bottom: 10px; }
.category-card h4 { font-size: 16px; margin-bottom: 6px; color: var(--text); margin-top: 0; }
.category-card p { font-size: 13px; color: var(--text-light); margin-bottom: 8px; }
.category-card .card-count {
    display: inline-block;
    background: var(--primary-light);
    color: var(--primary);
    padding: 2px 12px;
    border-radius: 12px;
    font-size: 12px;
}
/* mobile: 2 per row on extra small screens */
@media (max-width: 767px) {
    .category-cards .col-xs-6:nth-child(odd) { padding-right: 10px; }
    .category-cards .col-xs-6:nth-child(even) { padding-left: 10px; }
}

/* ========== 内容布局 ========== */
.content-layout { margin-bottom: 40px; }

/* ========== 文章卡片 ========== */
.article-card {
    background: var(--bg-white);
    border-radius: var(--radius);
    overflow: hidden;
    border: 1px solid var(--border);
    transition: var(--transition);
    margin-bottom: 20px;
}
.article-card:hover { box-shadow: var(--shadow-md); transform: translateY(-2px); }
.card-thumb {
    display: block;
    height: 180px;
    overflow: hidden;
    background: var(--primary-light);
}
.card-thumb img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.3s;
}
.article-card:hover .card-thumb img { transform: scale(1.05); }
.card-body { padding: 16px; }
.card-cat {
    display: inline-block;
    background: var(--primary-light);
    color: var(--primary);
    padding: 2px 10px;
    border-radius: 4px;
    font-size: 12px;
    margin-bottom: 8px;
}
.card-body h4 { font-size: 16px; margin-bottom: 8px; line-height: 1.4; margin-top: 0; }
.card-body h4 a { color: var(--text); }
.card-body h4 a:hover { color: var(--primary); }
.card-body p { font-size: 13px; color: var(--text-light); margin-bottom: 12px; line-height: 1.5; }
.card-footer {
    display: flex;
    gap: 12px;
    font-size: 12px;
    color: var(--text-lighter);
    padding-top: 12px;
    border-top: 1px solid var(--border);
}

/* ========== 文章列表 ========== */
.article-list-item {
    display: flex;
    align-items: stretch;
    gap: 0;
    background: var(--bg-white);
    border-radius: 12px;
    border: none;
    box-shadow: 0 2px 12px rgba(0,0,0,0.06);
    margin-bottom: 20px;
    overflow: hidden;
    transition: all 0.3s ease;
}
.article-list-item:hover {
    box-shadow: 0 8px 28px rgba(0,0,0,0.12);
    transform: translateY(-3px);
}
.article-list-item:hover .list-thumb img {
    transform: scale(1.06);
}
.list-thumb {
    flex: 0 0 280px;
    width: 280px;
    height: 180px;
    overflow: hidden;
    position: relative;
    display: block;
    background: linear-gradient(135deg, #eef2ff 0%, #e0e7ff 100%);
}
.list-thumb img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
    transition: transform 0.5s ease;
}
.list-body {
    flex: 1;
    min-width: 0;
    padding: 22px 26px;
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
}
.list-cat-badge {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    align-self: flex-start;
    background: #eef2ff;
    color: #4f46e5;
    padding: 4px 10px;
    border-radius: 4px;
    font-size: 12px;
    font-weight: 500;
    margin-bottom: 10px;
}
.list-body h4 {
    font-size: 19px;
    font-weight: 700;
    margin: 0 0 10px 0;
    line-height: 1.35;
}
.list-body h4 a {
    color: #1e293b;
    transition: color 0.2s;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}
.list-body h4 a:hover {
    color: var(--primary);
    text-decoration: none;
}
.list-body > p {
    font-size: 14px;
    color: #64748b;
    line-height: 1.7;
    margin-bottom: 14px;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}
.list-meta {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 13px;
    color: #94a3b8;
    flex-wrap: wrap;
    margin-top: auto;
    padding-top: 6px;
}
.list-meta-item {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 4px 10px;
    background: #f8fafc;
    border-radius: 20px;
    white-space: nowrap;
}
.list-meta-item.cat {
    background: #eef2ff;
    color: #4f46e5;
    font-weight: 500;
}
.list-meta-sep {
    color: #cbd5e1;
    user-select: none;
}
.list-read-more {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    color: #fff;
    background: #4f46e5;
    font-weight: 500;
    font-size: 12px;
    padding: 6px 14px;
    border-radius: 20px;
    margin-left: auto;
    transition: all 0.2s ease;
}
.list-read-more:hover {
    background: #4338ca;
    text-decoration: none;
    color: #fff;
    box-shadow: 0 4px 12px rgba(79,70,229,0.3);
}
.badge-top {
    display: inline-block;
    background: var(--accent);
    color: #fff;
    padding: 1px 8px;
    border-radius: 4px;
    font-size: 12px;
    margin-right: 6px;
}

/* ========== 侧边栏搜索框 ========== */
.sidebar-search-box {
    background: var(--bg-white);
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
    padding: 18px 20px;
    margin-bottom: 20px;
    border: 1px solid var(--border);
}
.sidebar-search-box .form-control {
    border-radius: 8px 0 0 8px;
    border-color: var(--border);
    box-shadow: none;
    height: 44px;
    font-size: 15px;
    transition: border-color 0.2s;
}
.sidebar-search-box .form-control:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(79,70,229,0.1);
}
.sidebar-search-box .btn-primary {
    border-radius: 0 8px 8px 0;
    height: 44px;
    padding: 0 18px;
    font-size: 15px;
    font-weight: 500;
    background: var(--primary);
    border-color: var(--primary);
}
.sidebar-search-box .btn-primary:hover {
    background: var(--primary-dark);
    border-color: var(--primary-dark);
}
.sidebar-search-box .input-group {
    width: 100%;
}

/* ========== 侧边栏 ========== */
.sidebar .panel {
    border-radius: var(--radius);
    border-color: var(--border);
    box-shadow: var(--shadow);
}
.sidebar .panel-heading {
    background: var(--bg-white);
    border-bottom: 2px solid var(--primary-light);
    border-radius: var(--radius) var(--radius) 0 0;
}
.sidebar .panel-title { font-size: 16px; font-weight: 600; color: var(--text); }
.sidebar .list-group-item { border-color: var(--border); padding: 10px 15px; }
.hot-list-item a { color: var(--text); }
.hot-list-item a:hover { color: var(--primary); }
.hot-rank {
    margin-right: 8px;
}
.hot-rank.hot { background-color: var(--accent) !important; color: #fff !important; }
.tag-cloud { display: flex; flex-wrap: wrap; gap: 8px; }
.tag-item {
    padding: 4px 12px;
    background: var(--bg);
    border-radius: 20px;
    font-size: 13px;
    color: var(--text-light);
    transition: var(--transition);
    display: inline-block;
}
.tag-item:hover { background: var(--primary); color: #fff; text-decoration: none; }

/* ========== 文章详情 ========== */
.article-detail {
    background: var(--bg-white);
    border-radius: var(--radius);
    padding: 30px;
    border: 1px solid var(--border);
    margin-bottom: 30px;
}
.article-header { margin-bottom: 24px; padding-bottom: 24px; border-bottom: 1px solid var(--border); }
.article-header h1 { font-size: 28px; line-height: 1.4; margin: 0 0 16px 0; }
.article-meta { display: flex; flex-wrap: wrap; gap: 16px; font-size: 14px; color: var(--text-light); }
.article-cover { margin-bottom: 24px; border-radius: var(--radius-sm); overflow: hidden; }
.article-cover img { width: 100%; max-height: 400px; object-fit: cover; }
.article-content { font-size: 16px; line-height: 1.9; }
.article-content h2 { font-size: 22px; margin: 24px 0 12px; }
.article-content h3 { font-size: 18px; margin: 20px 0 10px; }
.article-content p { margin-bottom: 14px; }
.article-content img { max-width: 100%; border-radius: var(--radius-sm); margin: 12px 0; }
.article-content ul, .article-content ol { padding-left: 24px; margin-bottom: 14px; }
.article-content li { margin-bottom: 6px; }
.article-content blockquote {
    border-left: 4px solid var(--primary);
    padding: 12px 20px;
    background: var(--primary-light);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    margin: 16px 0;
    font-size: inherit;
}
.article-content img { max-width: 100%; border-radius: var(--radius-sm); margin: 12px 0; }
.article-content a { color: var(--primary); }
.article-content table {
    width: 100%;
    border-collapse: collapse;
    margin: 16px 0;
}
.article-content table td,
.article-content table th {
    border: 1px solid var(--border);
    padding: 8px 12px;
}

.article-actions {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-top: 30px;
    padding-top: 24px;
    border-top: 1px solid var(--border);
    flex-wrap: wrap;
}
.btn-like {
    background: linear-gradient(135deg, #F59E0B, #EF4444) !important;
    color: #fff !important;
    border: none !important;
    border-radius: 24px !important;
    font-size: 16px;
}
.btn-like:hover {
    transform: scale(1.05);
    box-shadow: 0 4px 12px rgba(239,68,68,0.3);
    color: #fff !important;
}
.action-hint { font-size: 14px; }
.article-source { margin-top: 16px; padding: 12px; background: var(--bg); border-radius: var(--radius-sm); font-size: 14px; color: var(--text-light); }

/* ========== 搜索/分类/空状态 ========== */
.search-header, .category-header { padding: 20px 0; text-align: center; }
.search-header h2 { font-size: 22px; margin-bottom: 8px; margin-top: 0; }
.category-icon-large { font-size: 48px; display: block; margin-bottom: 10px; }
.category-info h2 { font-size: 24px; margin-bottom: 8px; margin-top: 0; }
.category-info p { color: var(--text-light); margin-bottom: 6px; }
.empty-state { text-align: center; padding: 60px 20px; color: var(--text-light); }
.empty-state .btn { margin-top: 12px; }

/* ========== 底部分页 ========== */
.pagination > li > a,
.pagination > li > span {
    border-radius: var(--radius-sm);
    margin: 0 3px;
    border-color: var(--border);
    color: var(--text);
}
.pagination > .active > a,
.pagination > .active > span,
.pagination > .active > a:hover,
.pagination > .active > span:hover,
.pagination > li > a:hover {
    background: var(--primary);
    border-color: var(--primary);
    color: #fff;
}

/* ========== 底部 ========== */
.site-footer {
    background: linear-gradient(180deg, #1e293b 0%, #111827 100%);
    color: #cbd5e1;
    padding: 50px 0 0;
    margin-top: 50px;
    border-top: 4px solid var(--primary);
}
.footer-grid {
    margin-bottom: 20px;
}
.footer-col {
    margin-bottom: 30px;
}
.footer-col h4 {
    color: #fff;
    font-size: 17px;
    font-weight: 600;
    margin-bottom: 18px;
    margin-top: 0;
    padding-bottom: 10px;
    position: relative;
    letter-spacing: 0.5px;
}
.footer-col h4::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 36px;
    height: 3px;
    background: var(--primary);
    border-radius: 2px;
}
.footer-col p {
    font-size: 14px;
    line-height: 1.8;
    color: #94a3b8;
}
.footer-col ul {
    padding-left: 0;
}
.footer-col ul li {
    margin-bottom: 10px;
    position: relative;
    padding-left: 16px;
}
.footer-col ul li::before {
    content: '›';
    position: absolute;
    left: 0;
    top: -1px;
    color: var(--primary);
    font-weight: 700;
    font-size: 16px;
}
.footer-col ul li a {
    color: #94a3b8;
    font-size: 14px;
    transition: all 0.25s ease;
    display: inline-block;
}
.footer-col ul li a:hover {
    color: #fff;
    text-decoration: none;
    padding-left: 6px;
}
.footer-contact-item {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    margin-bottom: 10px;
    font-size: 14px;
    color: #94a3b8;
    line-height: 1.6;
}
.footer-contact-item .contact-icon {
    flex-shrink: 0;
    width: 20px;
    text-align: center;
    font-size: 15px;
    color: var(--primary);
    margin-top: 1px;
}
.footer-bottom {
    padding: 18px 0;
    border-top: 1px solid rgba(255,255,255,0.08);
    font-size: 13px;
    color: #64748b;
    text-align: center;
}
.footer-bottom p {
    margin-bottom: 3px;
}
.footer-bottom a {
    color: #94a3b8;
    transition: color 0.2s;
}
.footer-bottom a:hover {
    color: #fff;
    text-decoration: none;
}

@media (max-width: 767px) {
    .site-footer {
        padding: 36px 0 0;
        margin-top: 30px;
    }
    .footer-col {
        margin-bottom: 24px;
    }
    .footer-col h4 {
        font-size: 16px;
        margin-bottom: 12px;
        padding-bottom: 8px;
    }
    .footer-col p,
    .footer-col ul li a,
    .footer-contact-item {
        font-size: 13px;
    }
}

/* ========== 通用组件 ========== */
.btn-primary {
    background: var(--primary);
    border-color: var(--primary);
}
.btn-primary:hover, .btn-primary:focus {
    background: var(--primary-dark);
    border-color: var(--primary-dark);
}

/* 响应式补充 */
@media (max-width: 767px) {
    .hero-slide { padding: 40px 20px; }
    .hero-content h2 { font-size: 22px; }
    .hero-content p { font-size: 14px; }
    .article-detail { padding: 15px; }
    .article-header h1 { font-size: 22px; }
    .article-list-item { flex-direction: column; margin-bottom: 16px; }
    .list-thumb { width: 100% !important; height: 200px; min-height: auto; }
    .list-thumb img { height: 100%; }
    .list-body { padding: 16px 18px; }
    .list-body h4 { font-size: 17px; }
    .list-meta { gap: 4px; padding-top: 10px; }
    .list-meta-item { padding: 3px 8px; font-size: 12px; }
    .list-read-more { margin-left: 0; padding: 5px 12px; }
    .site-navbar .navbar-form {
        border-top: none;
        border-bottom: 1px solid var(--border);
        box-shadow: none;
        margin: 0 -15px;
        padding: 10px 15px;
    }
    .site-navbar .navbar-form .input-group { max-width: 100%; }
    .category-cards .category-card { margin-bottom: 15px; padding: 16px 12px; }
    .category-cards .category-card h4 { font-size: 14px; }
    .category-cards .category-card .card-icon { font-size: 28px; }
    .sidebar-search-box { padding: 14px 16px; }
    .sidebar-search-box .form-control,
    .sidebar-search-box .btn-primary { height: 40px; font-size: 14px; }
}