/* =============================================
   探花 - 主样式文件
   品牌色彩方案：橙色#FF6B35 深蓝#004E89 金黄#F7B801
   ============================================= */

/* CSS变量定义 */
:root {
    --primary: #FF6B35;
    --primary-dark: #E55A25;
    --secondary: #004E89;
    --secondary-dark: #003A66;
    --accent: #F7B801;
    --accent-dark: #D9A200;
    --danger: #E63946;
    --success: #2DC653;
    --bg-light: #F8F9FA;
    --bg-white: #FFFFFF;
    --text-dark: #1A1A1A;
    --text-gray: #555555;
    --text-light: #888888;
    --border: #E0E0E0;
    --shadow: 0 4px 20px rgba(0,0,0,0.1);
    --shadow-hover: 0 8px 30px rgba(0,0,0,0.18);
    --radius: 12px;
    --radius-sm: 6px;
    --transition: all 0.3s ease;
}

/* 基础重置 */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: 'PingFang SC', 'Microsoft YaHei', 'Noto Sans CJK SC', sans-serif;
    color: var(--text-dark);
    background: var(--bg-light);
    line-height: 1.7;
    overflow-x: hidden;
}

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

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

ul, ol { list-style: none; }

/* =============================================
   顶部公告栏
   ============================================= */
.top-bar {
    background: linear-gradient(90deg, var(--secondary) 0%, var(--primary) 100%);
    color: #fff;
    font-size: 13px;
    padding: 8px 0;
    text-align: center;
}

.top-bar-inner {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
}

.top-bar a { 
    color: var(--accent); 
    font-weight: 600;
    text-decoration: none;
}

.top-bar-links {
    display: flex;
    gap: 20px;
    align-items: center;
}

.top-bar-links a {
    white-space: nowrap;
}

/* =============================================
   导航栏
   ============================================= */
.header {
    background: var(--bg-white);
    box-shadow: 0 2px 12px rgba(0,0,0,0.08);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.header .container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 20px;
}

.nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
    gap: 30px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    flex-shrink: 0;
    text-decoration: none;
}

.logo-img {
    height: 44px;
    width: auto;
}

.logo-text {
    font-size: 22px;
    font-weight: 800;
    color: var(--primary);
    letter-spacing: -0.5px;
}

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

/* 导航菜单 */
.nav-menu {
    display: flex;
    align-items: center;
    gap: 0;
    flex: 1;
    list-style: none;
    margin: 0;
    padding: 0;
}

.nav-menu > li {
    position: relative;
}

.nav-menu > li > a {
    display: block;
    padding: 10px 16px;
    font-size: 14px;
    font-weight: 600;
    color: var(--text-dark);
    border-radius: var(--radius-sm);
    transition: var(--transition);
    white-space: nowrap;
    text-decoration: none;
}

.nav-menu > li > a:hover,
.nav-menu > li > a.active {
    color: var(--primary);
    background: rgba(255,107,53,0.08);
}

.arrow {
    font-size: 12px;
    margin-left: 4px;
}

/* 下拉菜单 */
.has-dropdown {
    position: relative;
}

.dropdown {
    position: absolute;
    top: calc(100% + 8px);
    left: 0;
    background: var(--bg-white);
    border-radius: var(--radius);
    box-shadow: var(--shadow-hover);
    min-width: 180px;
    padding: 8px 0;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-8px);
    transition: var(--transition);
    z-index: 100;
    list-style: none;
    margin: 0;
}

.has-dropdown:hover .dropdown {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown li a {
    display: block;
    padding: 10px 18px;
    font-size: 13px;
    color: var(--text-gray);
    text-decoration: none;
    transition: var(--transition);
}

.dropdown li a:hover {
    color: var(--primary);
    background: rgba(255,107,53,0.06);
}

/* 导航操作区 */
.nav-actions {
    display: flex;
    align-items: center;
    gap: 12px;
    flex-shrink: 0;
}

.search-wrap {
    display: flex;
    align-items: center;
    background: var(--bg-light);
    border: 2px solid var(--border);
    border-radius: 30px;
    overflow: hidden;
    transition: var(--transition);
}

.search-wrap:focus-within {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(255,107,53,0.12);
}

.search-input {
    flex: 1;
    border: none;
    outline: none;
    padding: 10px 16px;
    font-size: 14px;
    background: transparent;
    color: var(--text-dark);
    min-width: 150px;
}

.search-btn {
    background: var(--primary);
    border: none;
    color: #fff;
    padding: 10px 16px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 6px;
}

.search-btn:hover {
    background: var(--primary-dark);
}

/* 汉堡菜单 */
.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    padding: 6px;
    background: none;
    border: none;
}

.hamburger span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--text-dark);
    border-radius: 2px;
    transition: var(--transition);
}

/* =============================================
   面包屑
   ============================================= */
.breadcrumb {
    background: var(--bg-white);
    border-bottom: 1px solid var(--border);
    padding: 10px 0;
}

.breadcrumb-inner {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 13px;
    color: var(--text-light);
}

.breadcrumb-inner a {
    color: var(--text-light);
}

.breadcrumb-inner a:hover {
    color: var(--primary);
}

.breadcrumb-inner span.sep {
    color: var(--border);
}

.breadcrumb-inner span.current {
    color: var(--text-dark);
    font-weight: 600;
}

/* =============================================
   容器与布局
   ============================================= */
.container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 20px;
}

.section {
    padding: 60px 0;
}

.section-sm {
    padding: 40px 0;
}

.section-title {
    text-align: center;
    margin-bottom: 40px;
}

.section-title h2 {
    font-size: 32px;
    font-weight: 800;
    color: var(--text-dark);
    margin-bottom: 12px;
    position: relative;
    display: inline-block;
}

.section-title h2::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    border-radius: 2px;
}

.section-title p {
    font-size: 16px;
    color: var(--text-gray);
    margin-top: 20px;
}

/* =============================================
   网格布局
   ============================================= */
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 24px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }
.grid-5 { display: grid; grid-template-columns: repeat(5, 1fr); gap: 24px; }
.grid-6 { display: grid; grid-template-columns: repeat(6, 1fr); gap: 24px; }

/* =============================================
   首页英雄区
   ============================================= */
.hero {
    background: linear-gradient(135deg, #0D1B2A 0%, #1A2E42 100%);
    padding: 80px 0;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -10%;
    width: 500px;
    height: 500px;
    background: rgba(255,107,53,0.1);
    border-radius: 50%;
    z-index: 0;
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-text h1 {
    font-size: 48px;
    font-weight: 900;
    color: #fff;
    line-height: 1.2;
    margin-bottom: 20px;
}

.hero-text h1 span {
    color: var(--primary);
}

.hero-text p {
    font-size: 18px;
    color: rgba(255,255,255,0.8);
    margin-bottom: 30px;
    line-height: 1.8;
}

.hero-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-bottom: 30px;
}

.hero-tag {
    background: rgba(255,107,53,0.2);
    color: var(--accent);
    padding: 6px 14px;
    border-radius: 20px;
    font-size: 13px;
    font-weight: 600;
}

.hero-btns {
    display: flex;
    gap: 16px;
}

.btn {
    padding: 12px 32px;
    border-radius: var(--radius);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    border: none;
    transition: var(--transition);
    text-decoration: none;
    display: inline-block;
}

.btn-primary {
    background: var(--primary);
    color: #fff;
}

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(255,107,53,0.3);
}

.btn-secondary {
    background: transparent;
    color: #fff;
    border: 2px solid #fff;
}

.btn-secondary:hover {
    background: #fff;
    color: var(--secondary);
}

.hero-stats {
    display: flex;
    gap: 40px;
    margin-top: 40px;
}

.hero-stat {
    text-align: center;
}

.hero-stat .num {
    font-size: 32px;
    font-weight: 900;
    color: var(--primary);
}

.hero-stat .label {
    font-size: 13px;
    color: rgba(255,255,255,0.6);
    margin-top: 4px;
}

.hero-visual {
    position: relative;
    height: 400px;
}

.hero-visual img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: var(--radius);
}

/* =============================================
   视频卡片
   ============================================= */
.video-card {
    background: var(--bg-white);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: 0 2px 12px rgba(0,0,0,0.08);
    transition: var(--transition);
    position: relative;
}

.video-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-hover);
}

.video-thumb {
    position: relative;
    width: 100%;
    padding-bottom: 56.25%;
    background: #000;
    overflow: hidden;
}

.video-thumb img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.video-play {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 60px;
    height: 60px;
    background: rgba(255,107,53,0.9);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: var(--transition);
    cursor: pointer;
}

.video-play::after {
    content: '▶';
    color: #fff;
    font-size: 20px;
    margin-left: 3px;
}

.video-card:hover .video-play {
    opacity: 1;
}

.video-info {
    padding: 16px;
}

.video-badge {
    display: inline-block;
    background: var(--primary);
    color: #fff;
    padding: 4px 10px;
    border-radius: 4px;
    font-size: 11px;
    font-weight: 600;
    margin-bottom: 8px;
}

.video-title {
    font-size: 14px;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 8px;
    line-height: 1.5;
}

.video-stats {
    display: flex;
    gap: 12px;
    font-size: 12px;
    color: var(--text-light);
}

.video-stat {
    display: flex;
    align-items: center;
    gap: 4px;
}

/* =============================================
   页面英雄区
   ============================================= */
.page-hero {
    background: linear-gradient(135deg, var(--secondary) 0%, var(--primary) 100%);
    color: #fff;
    padding: 60px 0;
    text-align: center;
}

.page-hero h1 {
    font-size: 42px;
    font-weight: 900;
    margin-bottom: 16px;
}

.page-hero p {
    font-size: 16px;
    opacity: 0.9;
}

/* =============================================
   专家卡片
   ============================================= */
.expert-card {
    background: var(--bg-white);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: 0 2px 12px rgba(0,0,0,0.08);
    transition: var(--transition);
    text-align: center;
}

.expert-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-hover);
}

.expert-avatar {
    width: 120px;
    height: 120px;
    border-radius: 50%;
    margin: 24px auto 16px;
    overflow: hidden;
    background: var(--bg-light);
}

.expert-avatar img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.expert-name {
    font-size: 16px;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 4px;
}

.expert-title {
    font-size: 13px;
    color: var(--primary);
    font-weight: 600;
    margin-bottom: 12px;
}

.expert-desc {
    font-size: 13px;
    color: var(--text-gray);
    line-height: 1.6;
    padding: 0 16px 16px;
}

.expert-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    justify-content: center;
    padding: 0 16px 16px;
}

.expert-tag {
    background: rgba(255,107,53,0.1);
    color: var(--primary);
    padding: 4px 10px;
    border-radius: 12px;
    font-size: 11px;
    font-weight: 600;
}

/* =============================================
   特性卡片
   ============================================= */
.feature-card {
    background: var(--bg-white);
    border-radius: var(--radius);
    padding: 32px;
    text-align: center;
    transition: var(--transition);
    border: 1px solid var(--border);
}

.feature-card:hover {
    border-color: var(--primary);
    box-shadow: 0 8px 24px rgba(255,107,53,0.12);
    transform: translateY(-4px);
}

.feature-icon {
    width: 64px;
    height: 64px;
    background: rgba(255,107,53,0.1);
    color: var(--primary);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 28px;
    margin: 0 auto 16px;
}

.feature-card h3 {
    font-size: 16px;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 12px;
}

.feature-card p {
    font-size: 13px;
    color: var(--text-gray);
    line-height: 1.6;
}

/* =============================================
   用户评价
   ============================================= */
.review-card {
    background: var(--bg-white);
    border-radius: var(--radius);
    padding: 24px;
    box-shadow: 0 2px 12px rgba(0,0,0,0.08);
}

.review-stars {
    color: var(--accent);
    font-size: 14px;
    margin-bottom: 12px;
}

.review-text {
    font-size: 13px;
    color: var(--text-gray);
    line-height: 1.8;
    margin-bottom: 16px;
}

.review-author {
    display: flex;
    align-items: center;
    gap: 12px;
}

.review-avatar {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: var(--bg-light);
    overflow: hidden;
}

.review-avatar img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.review-name {
    font-size: 13px;
    font-weight: 600;
    color: var(--text-dark);
}

.review-title {
    font-size: 11px;
    color: var(--text-light);
}

/* =============================================
   FAQ手风琴
   ============================================= */
.faq-item {
    background: var(--bg-white);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    margin-bottom: 12px;
    overflow: hidden;
}

.faq-question {
    padding: 18px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-weight: 600;
    color: var(--text-dark);
    transition: var(--transition);
}

.faq-question:hover {
    background: rgba(255,107,53,0.04);
    color: var(--primary);
}

.faq-toggle {
    font-size: 18px;
    transition: var(--transition);
}

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

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
    padding: 0 18px;
}

.faq-item.active .faq-answer {
    max-height: 500px;
    padding: 0 18px 18px;
}

.faq-answer p {
    color: var(--text-gray);
    line-height: 1.8;
    font-size: 13px;
}

/* =============================================
   社区功能卡片
   ============================================= */
.community-card {
    background: linear-gradient(135deg, rgba(255,107,53,0.1) 0%, rgba(0,78,137,0.1) 100%);
    border-radius: var(--radius);
    padding: 32px;
    text-align: center;
    border: 1px solid rgba(255,107,53,0.2);
    transition: var(--transition);
}

.community-card:hover {
    transform: translateY(-4px);
    border-color: var(--primary);
    box-shadow: 0 8px 24px rgba(255,107,53,0.12);
}

.community-icon {
    font-size: 36px;
    margin-bottom: 16px;
}

.community-card h3 {
    font-size: 16px;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 12px;
}

.community-card p {
    font-size: 13px;
    color: var(--text-gray);
    line-height: 1.6;
    margin-bottom: 16px;
}

.community-stat {
    font-size: 14px;
    font-weight: 600;
    color: var(--primary);
    margin-bottom: 16px;
}

/* =============================================
   如何加入步骤
   ============================================= */
.howto-steps {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
    position: relative;
}

.howto-steps::before {
    content: '';
    position: absolute;
    top: 50px;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    z-index: 0;
}

.howto-step {
    position: relative;
    z-index: 1;
}

.howto-num {
    width: 50px;
    height: 50px;
    background: var(--primary);
    color: #fff;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    font-weight: 700;
    margin: 0 auto 16px;
}

.howto-step h3 {
    font-size: 16px;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 8px;
}

.howto-step p {
    font-size: 13px;
    color: var(--text-gray);
    line-height: 1.6;
}

/* =============================================
   AI赋能模块
   ============================================= */
.ai-section {
    background: linear-gradient(135deg, #0D1B2A 0%, #1A2E42 100%);
    padding: 60px 0;
}

.ai-section .section-title h2 {
    color: #fff;
}

.ai-section .section-title h2::after {
    background: linear-gradient(90deg, var(--primary), var(--accent));
}

.ai-section .section-title p {
    color: rgba(255,255,255,0.7);
}

.ai-card {
    background: rgba(255,255,255,0.06);
    border: 1px solid rgba(255,255,255,0.1);
    border-radius: var(--radius);
    padding: 28px;
    transition: var(--transition);
    backdrop-filter: blur(8px);
}

.ai-card:hover {
    background: rgba(255,255,255,0.1);
    transform: translateY(-4px);
    border-color: rgba(255,107,53,0.4);
}

.ai-card .feature-icon {
    background: rgba(255,107,53,0.15);
    color: var(--primary);
}

.ai-card h3 {
    color: #fff;
}

.ai-card p {
    color: rgba(255,255,255,0.65);
}

/* =============================================
   页脚
   ============================================= */
.footer {
    background: var(--secondary);
    color: #fff;
    padding: 60px 0 20px;
}

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

.footer-col h4 {
    font-size: 14px;
    font-weight: 700;
    margin-bottom: 16px;
    color: var(--accent);
}

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

.footer-col ul li {
    margin-bottom: 10px;
}

.footer-col a {
    color: rgba(255,255,255,0.7);
    font-size: 13px;
    transition: var(--transition);
}

.footer-col a:hover {
    color: #fff;
}

.footer-desc {
    font-size: 13px;
    color: rgba(255,255,255,0.7);
    line-height: 1.8;
    margin-bottom: 16px;
}

.footer-social {
    display: flex;
    gap: 12px;
}

.social-btn {
    width: 36px;
    height: 36px;
    background: rgba(255,255,255,0.1);
    border: 1px solid rgba(255,255,255,0.2);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #fff;
    cursor: pointer;
    transition: var(--transition);
    font-size: 14px;
}

.social-btn:hover {
    background: var(--primary);
    border-color: var(--primary);
}

.footer-bottom {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-top: 20px;
    border-top: 1px solid rgba(255,255,255,0.1);
    font-size: 12px;
    color: rgba(255,255,255,0.6);
}

.footer-links {
    display: flex;
    gap: 20px;
}

.footer-links a {
    color: rgba(255,255,255,0.6);
    transition: var(--transition);
}

.footer-links a:hover {
    color: #fff;
}

/* =============================================
   响应式设计
   ============================================= */
@media (max-width: 1200px) {
    .grid-6 { grid-template-columns: repeat(4, 1fr); }
    .footer-grid { grid-template-columns: 1.5fr 1fr 1fr; }
    .footer-grid > div:last-child { grid-column: 1 / -1; }
}

@media (max-width: 992px) {
    .hero-content { grid-template-columns: 1fr; gap: 32px; }
    .hero-text h1 { font-size: 36px; }
    .hero-visual { display: none; }
    .grid-4 { grid-template-columns: repeat(2, 1fr); }
    .grid-5 { grid-template-columns: repeat(3, 1fr); }
    .howto-steps { grid-template-columns: repeat(2, 1fr); }
    .howto-steps::before { display: none; }
    .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
    .nav {
        flex-wrap: wrap;
        gap: 10px;
    }
    .nav-menu { 
        display: none;
        width: 100%;
    }
    .hamburger { display: flex; }
    .nav-menu.open {
        display: flex;
        flex-direction: column;
        position: fixed;
        top: 70px;
        left: 0;
        right: 0;
        bottom: 0;
        background: var(--bg-white);
        padding: 20px;
        overflow-y: auto;
        z-index: 999;
        gap: 0;
    }
    .nav-menu.open > li > a {
        padding: 12px 16px;
        border-radius: 6px;
    }
    .dropdown {
        position: static;
        opacity: 1;
        visibility: visible;
        transform: none;
        box-shadow: none;
        background: rgba(255,107,53,0.04);
        margin-top: 4px;
        margin-left: 16px;
    }
    .nav-actions {
        width: 100%;
        order: -1;
    }
    .grid-3 { grid-template-columns: repeat(2, 1fr); }
    .grid-6 { grid-template-columns: repeat(2, 1fr); }
    .section { padding: 40px 0; }
    .section-title h2 { font-size: 26px; }
    .footer-grid { grid-template-columns: 1fr; }
    .footer-bottom { flex-direction: column; text-align: center; }
    .hero-text h1 { font-size: 30px; }
    .page-hero h1 { font-size: 28px; }
    .howto-steps { grid-template-columns: 1fr; }
    .search-tags { display: none; }
}

@media (max-width: 480px) {
    .grid-2 { grid-template-columns: 1fr; }
    .grid-3 { grid-template-columns: 1fr; }
    .grid-4 { grid-template-columns: 1fr; }
    .hero-btns { flex-direction: column; }
    .hero-stats { gap: 16px; }
    .hero-stat .num { font-size: 22px; }
    .nav { height: auto; gap: 8px; }
    .logo-text { font-size: 18px; }
    .search-wrap { max-width: 100%; }
    .search-input { min-width: auto; }
    .hero-text h1 { font-size: 24px; }
    .section-title h2 { font-size: 22px; }
}

/* =============================================
   工具类
   ============================================= */
.text-center { text-align: center; }
.text-right { text-align: right; }
.mt-20 { margin-top: 20px; }
.mt-40 { margin-top: 40px; }
.mb-20 { margin-bottom: 20px; }
.mb-40 { margin-bottom: 40px; }
.hidden { display: none; }
.visible { display: block; }

/* 返回顶部按钮 */
#backToTop {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--primary);
    color: #fff;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: none;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    z-index: 999;
    transition: var(--transition);
    box-shadow: 0 4px 12px rgba(255,107,53,0.3);
}

#backToTop:hover {
    background: var(--primary-dark);
    transform: translateY(-3px);
    box-shadow: 0 8px 20px rgba(255,107,53,0.4);
}

#backToTop.show {
    display: flex;
}