/* 全局样式 */
:root {
    /* 海洋主题配色 */
    --primary-color: #006994;
    --secondary-color: #00B4D8;
    --accent-color: #48CAE4;
    --light-color: #ADE8F4;
    --dark-color: #03045E;
    --white-color: #FFFFFF;
    --text-color: #333333;
    --text-light: #666666;
    
    /* 辅助颜色 */
    --success-color: #2ECC71;
    --warning-color: #F39C12;
    --danger-color: #E74C3C;
    
    /* 字体 */
    --font-family: 'Montserrat', sans-serif;
    
    /* 间距 */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 3rem;
    --spacing-xl: 4rem;
    
    /* 边框半径 */
    --border-radius-sm: 4px;
    --border-radius-md: 8px;
    --border-radius-lg: 16px;
    
    /* 阴影 */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.15);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.2);
    
    /* 过渡 */
    --transition: all 0.3s ease;
}

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

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--white-color);
    overflow-x: hidden;
}

/* 容器 */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* 标题样式 */
.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
    text-align: center;
    margin-bottom: var(--spacing-lg);
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 4px;
    background: linear-gradient(90deg, var(--secondary-color), var(--accent-color));
    border-radius: 2px;
}

.section-subtitle {
    font-size: 1.8rem;
    font-weight: 600;
    color: var(--secondary-color);
    margin: var(--spacing-lg) 0 var(--spacing-md);
}

/* 按钮样式 */
.btn-primary, .btn-secondary {
    display: inline-block;
    padding: 12px 30px;
    font-size: 1rem;
    font-weight: 600;
    text-align: center;
    text-decoration: none;
    border: none;
    border-radius: var(--border-radius-md);
    cursor: pointer;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: var(--white-color);
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background-color: var(--white-color);
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

.btn-secondary:hover {
    background-color: var(--primary-color);
    color: var(--white-color);
}

/* 导航栏 */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: rgba(255, 255, 255, 0.95);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
    transition: var(--transition);
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-sm) var(--spacing-md);
    max-width: 1200px;
    margin: 0 auto;
}

.logo a {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
    transition: var(--transition);
}

.logo i {
    font-size: 2rem;
    color: var(--secondary-color);
}

.logo:hover a {
    color: var(--secondary-color);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--spacing-md);
    align-items: center;
}

.nav-item .nav-link {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    transition: var(--transition);
    position: relative;
    padding: 8px 0;
}

.nav-item .nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--secondary-color);
    transition: var(--transition);
}

.nav-item .nav-link:hover {
    color: var(--secondary-color);
}

.nav-item .nav-link:hover::after {
    width: 100%;
}

.hamburger {
    display: none;
    cursor: pointer;
}

.hamburger .bar {
    display: block;
    width: 25px;
    height: 3px;
    margin: 5px auto;
    transition: var(--transition);
    background-color: var(--primary-color);
}

/* 英雄区域 */
.hero {
    position: relative;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    overflow: hidden;
}

.hero-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(0, 105, 148, 0.6), rgba(0, 180, 216, 0.6)), 
                url('../images/ocean-hero.jpg');
    background-size: cover;
    background-position: center;
    z-index: -1;
    animation: oceanWave 20s ease-in-out infinite;
}

@keyframes oceanWave {
    0%, 100% { transform: scale(1) translate(0, 0); }
    50% { transform: scale(1.05) translate(0, -10px); }
}

.hero-content {
    color: var(--white-color);
    z-index: 1;
    max-width: 800px;
    padding: var(--spacing-md);
}

.hero-content h1 {
    font-size: 4rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
    animation: fadeInUp 1s ease-out;
}

.hero-content p {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-lg);
    text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.3);
    animation: fadeInUp 1s ease-out 0.2s both;
}

.hero-content .btn-primary {
    animation: fadeInUp 1s ease-out 0.4s both;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* 俱乐部介绍 */
.about {
    padding: var(--spacing-xl) 0;
    background-color: #f8fafc;
}

.about-content {
    display: grid;
    grid-template-columns: 2fr 3fr;
    gap: var(--spacing-lg);
    align-items: start;
    margin-bottom: var(--spacing-xl);
}

/* 确保视频容器可以充分利用宽度 */
.about-media-container {
    max-width: 100%;
    width: 100%;
    display: flex;
    flex-direction: column;
    gap: 0;
}

.club-media {
    margin-bottom: 0;
}

.media-gallery {
    display: block;
    gap: var(--spacing-sm);
    margin-top: 0;
}

/* 确保媒体项占据整个宽度 */
.media-item {
    width: 100% !important;
    margin: 0 !important;
    padding: 0 !important;
    display: block !important;
}

/* 确保视频保持16:9比例 */
.media-item video {
    width: 100% !important;
    aspect-ratio: 16 / 9 !important;
    height: auto !important;
    object-fit: cover !important;
    border: none !important;
    box-shadow: none !important;
    border-radius: 0 !important;
    background: transparent !important;
    padding: 0 !important;
    position: relative !important;
    overflow: hidden !important;
}

/* 移除海浪花边效果，让视频与背景融为一体 */
.media-item {
    position: relative !important;
    border-radius: 0 !important;
    overflow: hidden !important;
}

/* 移除海浪边框 */
.media-item::before {
    display: none !important;
}

/* 海浪边框动画 */
@keyframes waveBorder {
    0% {
        background-position: 0 0;
    }
    100% {
        background-position: 80px 80px;
    }
}

/* 确保图片占据足够空间 */
.media-item img {
    width: 100% !important;
    min-height: 350px !important;
    height: auto !important;
    object-fit: cover !important;
}

/* 移除可能存在的俱乐部环境标题 */
.club-media h3, .club-media .section-subtitle {
    display: none !important;
    margin: 0 !important;
    padding: 0 !important;
}

.about-text h3 {
    font-size: 1.5rem;
    color: var(--secondary-color);
    margin-bottom: var(--spacing-sm);
}

.about-text p {
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--text-light);
    margin-bottom: var(--spacing-md);
}

.about-image img {
    width: 100%;
    height: 400px;
    object-fit: cover;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-lg);
    transition: var(--transition);
}

.about-image img:hover {
    transform: scale(1.02);
}

/* 教练团队 */
.coaches-grid, .equipment-grid, .venues-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-md);
}

.coach-card, .equipment-card, .venue-card {
    background-color: var(--white-color);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-sm);
    overflow: hidden;
    transition: var(--transition);
}

.coach-card:hover, .equipment-card:hover, .venue-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.coach-image, .equipment-image, .venue-image {
    width: 100%;
    height: 250px;
    overflow: hidden;
}

.coach-image img, .equipment-image img, .venue-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition);
}

.coach-card:hover .coach-image img, .equipment-card:hover .equipment-image img, .venue-card:hover .venue-image img {
    transform: scale(1.1);
}

.coach-info, .equipment-info, .venue-info {
    padding: var(--spacing-md);
}

.coach-info h4, .equipment-info h4, .venue-info h4 {
    font-size: 1.3rem;
    color: var(--primary-color);
    margin-bottom: var(--spacing-xs);
}

.coach-info .coach-title, .equipment-info .equipment-specs {
    font-size: 1rem;
    color: var(--secondary-color);
    margin-bottom: var(--spacing-sm);
}

.coach-info p, .equipment-info p, .venue-info p {
    font-size: 0.95rem;
    color: var(--text-light);
    line-height: 1.6;
}

/* 潜水课程 */
.courses {
    padding: var(--spacing-xl) 0;
    background-color: var(--white-color);
}

.course-categories {
    display: flex;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
    flex-wrap: wrap;
}

.category-btn {
    padding: 12px 24px;
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-color);
    background-color: var(--white-color);
    border: 2px solid var(--light-color);
    border-radius: var(--border-radius-md);
    cursor: pointer;
    transition: var(--transition);
}

.category-btn.active {
    background-color: var(--primary-color);
    color: var(--white-color);
    border-color: var(--primary-color);
}

.category-btn:hover {
    background-color: var(--light-color);
    border-color: var(--accent-color);
}

.courses-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-md);
}

.course-card {
    background-color: var(--white-color);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-sm);
    overflow: hidden;
    transition: var(--transition);
    border-left: 4px solid var(--primary-color);
}

.course-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.course-header {
    padding: var(--spacing-md);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: var(--white-color);
}

.course-header h3 {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-xs);
}

.course-header .course-level {
    font-size: 1rem;
    opacity: 0.9;
}

.course-body {
    padding: var(--spacing-md);
}

.course-info {
    margin-bottom: var(--spacing-sm);
}

.course-info h4 {
    font-size: 1.1rem;
    color: var(--primary-color);
    margin-bottom: var(--spacing-xs);
}

.course-info p {
    font-size: 0.95rem;
    color: var(--text-light);
    line-height: 1.6;
}

.course-footer {
    padding: var(--spacing-md);
    background-color: #f8fafc;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-top: 1px solid var(--light-color);
}

.course-price {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

/* 课程表 */
.schedule {
    padding: var(--spacing-xl) 0;
    background-color: #f8fafc;
}

.schedule-search {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
    width: 100%;
}

.schedule-search .search-input {
    padding: 12px 20px;
    font-size: 1rem;
    border: 2px solid var(--light-color);
    border-radius: var(--border-radius-md);
    width: 400px;
    max-width: 100%;
    transition: var(--transition);
}

.schedule-search .search-input:focus {
    outline: none;
    border-color: var(--secondary-color);
    box-shadow: 0 0 0 3px rgba(0, 180, 216, 0.1);
}

.schedule-search .btn-primary {
    padding: 12px 30px;
    font-size: 1rem;
}

.schedule-controls {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.schedule-controls h3 {
    font-size: 1.5rem;
    color: var(--primary-color);
    margin: 0;
}

.schedule-table-container {
    overflow-x: auto;
    background-color: var(--white-color);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-sm);
}

.schedule-table {
    width: 100%;
    border-collapse: collapse;
}

.schedule-table th, .schedule-table td {
    padding: var(--spacing-sm);
    text-align: left;
    border-bottom: 1px solid var(--light-color);
}

.schedule-table th {
    background-color: var(--primary-color);
    color: var(--white-color);
    font-weight: 600;
    position: sticky;
    top: 0;
}

.schedule-table tr:hover {
    background-color: #f0f9ff;
}

.schedule-table tr.today {
    background-color: rgba(0, 180, 216, 0.1);
    font-weight: 500;
}

.progress-bar {
    height: 8px;
    background-color: var(--light-color);
    border-radius: 4px;
    overflow: hidden;
    margin-top: var(--spacing-xs);
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--secondary-color), var(--accent-color));
    border-radius: 4px;
    transition: width 0.3s ease;
}

/* 俱乐部活动 */
.activities {
    padding: var(--spacing-xl) 0;
    background-color: var(--white-color);
}

.activity-tabs {
    display: flex;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
    flex-wrap: wrap;
}

.tab-btn {
    padding: 12px 24px;
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-color);
    background-color: var(--white-color);
    border: 2px solid var(--light-color);
    border-radius: var(--border-radius-md);
    cursor: pointer;
    transition: var(--transition);
}

.tab-btn.active {
    background-color: var(--secondary-color);
    color: var(--white-color);
    border-color: var(--secondary-color);
}

.tab-btn:hover {
    background-color: var(--light-color);
    border-color: var(--accent-color);
}

.activities-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-md);
}

.activity-card {
    background-color: var(--white-color);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-sm);
    overflow: hidden;
    transition: var(--transition);
}

.activity-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.activity-image {
    width: 100%;
    height: 250px;
    overflow: hidden;
}

.activity-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition);
}

.activity-card:hover .activity-image img {
    transform: scale(1.1);
}

.activity-info {
    padding: var(--spacing-md);
}

.activity-info h4 {
    font-size: 1.3rem;
    color: var(--primary-color);
    margin-bottom: var(--spacing-xs);
}

.activity-meta {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-sm);
    font-size: 0.9rem;
    color: var(--text-light);
}

.activity-meta i {
    color: var(--secondary-color);
    margin-right: 5px;
}

.activity-info p {
    font-size: 0.95rem;
    color: var(--text-light);
    line-height: 1.6;
    margin-bottom: var(--spacing-md);
}

/* 精彩回顾 */
.gallery {
    padding: var(--spacing-xl) 0;
    background-color: #f8fafc;
}

.gallery-tabs {
    display: flex;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
}

.gallery-content {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: var(--spacing-md);
}

.gallery-item {
    position: relative;
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    cursor: pointer;
}

.gallery-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.gallery-item img, .gallery-item video {
    width: 100%;
    height: 250px;
    object-fit: cover;
    transition: var(--transition);
}

.gallery-item:hover img, .gallery-item:hover video {
    transform: scale(1.1);
}

.gallery-overlay {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background: linear-gradient(transparent, rgba(0, 0, 0, 0.8));
    color: var(--white-color);
    padding: var(--spacing-md);
    transform: translateY(100%);
    transition: var(--transition);
}

.gallery-item:hover .gallery-overlay {
    transform: translateY(0);
}

.gallery-overlay h4 {
    font-size: 1.1rem;
    margin-bottom: var(--spacing-xs);
}

.gallery-overlay p {
    font-size: 0.9rem;
    opacity: 0.9;
}

/* 联系我们 */
.contact {
    padding: var(--spacing-xl) 0;
    background-color: var(--white-color);
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-lg);
    align-items: start;
    justify-items: center;
}

.contact-info h3 {
    font-size: 1.5rem;
    color: var(--primary-color);
    margin-bottom: var(--spacing-md);
}

.contact-info p {
    font-size: 1.1rem;
    color: var(--text-light);
    margin-bottom: var(--spacing-sm);
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.contact-info i {
    color: var(--secondary-color);
    font-size: 1.2rem;
    width: 20px;
}

.social-links {
    display: flex;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-md);
}

.social-link {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 45px;
    height: 45px;
    background-color: var(--light-color);
    color: var(--primary-color);
    border-radius: 50%;
    text-decoration: none;
    transition: var(--transition);
    font-size: 1.2rem;
}

.social-link:hover {
    background-color: var(--primary-color);
    color: var(--white-color);
    transform: translateY(-3px);
}

/* 增大抖音四分之一音符图标 */
.social-link:nth-child(3) {
    font-size: 1.8rem;
}



/* 页脚 */
.footer {
    background: linear-gradient(135deg, var(--dark-color), var(--primary-color));
    color: var(--white-color);
    padding: var(--spacing-xl) 0 var(--spacing-md);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
}

.footer-logo i {
    font-size: 2rem;
    color: var(--accent-color);
}

.footer-info p {
    color: rgba(255, 255, 255, 0.8);
    margin-bottom: var(--spacing-sm);
}

.footer-links h4, .footer-contact h4 {
    font-size: 1.2rem;
    margin-bottom: var(--spacing-md);
    color: var(--accent-color);
}

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

.footer-links li {
    margin-bottom: var(--spacing-xs);
}

.footer-links a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: var(--transition);
}

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

.footer-contact p {
    color: rgba(255, 255, 255, 0.8);
    margin-bottom: var(--spacing-xs);
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.footer-contact i {
    color: var(--accent-color);
    font-size: 1rem;
    width: 18px;
}

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-md);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.6);
    font-size: 0.9rem;
}

/* 响应式设计 */
@media (max-width: 1024px) {
    .about-content, .contact-content {
        grid-template-columns: 1fr;
    }
    
    .hero-content h1 {
        font-size: 3rem;
    }
    
    .hero-content p {
        font-size: 1.2rem;
    }
}

@media (max-width: 768px) {
    .hamburger {
        display: block;
    }
    
    .hamburger.active .bar:nth-child(2) {
        opacity: 0;
    }
    
    .hamburger.active .bar:nth-child(1) {
        transform: translateY(8px) rotate(45deg);
    }
    
    .hamburger.active .bar:nth-child(3) {
        transform: translateY(-8px) rotate(-45deg);
    }
    
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        gap: 0;
        flex-direction: column;
        background-color: var(--white-color);
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: 0 10px 27px rgba(0, 0, 0, 0.05);
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .nav-item {
        margin: 16px 0;
    }
    
    .hero-content h1 {
        font-size: 2.5rem;
    }
    
    .hero-content p {
        font-size: 1.1rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .section-subtitle {
        font-size: 1.5rem;
    }
    
    .course-categories, .activity-tabs, .gallery-tabs {
        flex-direction: column;
        align-items: center;
    }
    
    .category-btn, .tab-btn {
        width: 200px;
    }
    
    .schedule-table {
        font-size: 0.9rem;
    }
    
    .schedule-table th, .schedule-table td {
        padding: 8px;
    }
}

@media (max-width: 480px) {
    .hero-content h1 {
        font-size: 2rem;
    }
    
    .hero-content p {
        font-size: 1rem;
    }
    
    .section-title {
        font-size: 1.8rem;
    }
    
    .about-image img {
        height: 300px;
    }
    
    .coaches-grid, .equipment-grid, .venues-grid, .courses-content, .activities-content, .gallery-content {
        grid-template-columns: 1fr;
    }
    
    .contact-form {
        padding: var(--spacing-md);
    }
}

/* 加载动画 */
.loading {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: var(--spacing-lg);
}

.loading-spinner {
    width: 50px;
    height: 50px;
    border: 5px solid var(--light-color);
    border-top: 5px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* 平滑滚动 */
html {
    scroll-behavior: smooth;
}

/* 回到顶部按钮 */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background-color: var(--primary-color);
    color: var(--white-color);
    border: none;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    cursor: pointer;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    opacity: 0;
    visibility: hidden;
    z-index: 999;
}

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

.back-to-top:hover {
    background-color: var(--secondary-color);
    transform: translateY(-5px);
}

/* 气泡装饰 */
.bubble {
    position: absolute;
    border-radius: 50%;
    background-color: rgba(255, 255, 255, 0.3);
    animation: bubbleRise 8s ease-in-out infinite;
}

@keyframes bubbleRise {
    0% {
        transform: translateY(0) scale(0);
        opacity: 0;
    }
    10% {
        opacity: 1;
    }
    90% {
        opacity: 1;
    }
    100% {
        transform: translateY(-1000px) scale(1);
        opacity: 0;
    }
}