/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Poppins', sans-serif;
    line-height: 1.6;
    color: #333;
}

/* Header and Navigation */
header {
    background-color: rgba(255, 255, 255, 0.95);
    box-shadow: 0 2px 15px rgba(0,0,0,0.1);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 5%;
    max-width: 1200px;
    margin: 0 auto;
}

.logo h1 {
    font-size: 1.5rem;
    color: #2c3e50;
    background: linear-gradient(45deg, #FF6B6B, #4ECDC4);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.nav-links a {
    text-decoration: none;
    color: #2c3e50;
    margin-left: 2rem;
    font-weight: 500;
    transition: all 0.3s ease;
    position: relative;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: linear-gradient(45deg, #FF6B6B, #4ECDC4);
    transition: width 0.3s ease;
}

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

.nav-links a:hover,
.nav-links a.active {
    color: #FF6B6B;
}

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background: linear-gradient(45deg, #FF6B6B, #4ECDC4);
    margin: 2px 0;
    transition: 0.3s;
}

/* Hero Section */
.hero {
    position: relative; /* 确保子元素绝对定位基于它 */
    height: 100vh;
    background: linear-gradient(rgba(0,0,0,0.5), rgba(0,0,0,0.5)), url('../images/hero-bg.jpg');
    background-size: cover;
    background-position: center;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: #fff;
    padding: 0 1rem;
    overflow: hidden; /* 防止视频溢出 */
}

.hero-video {
    position: absolute;
    top: 50%;
    left: 50%;
    min-width: 100%;
    min-height: 100%;
    width: auto;
    height: auto;
    z-index: 0;
    transform: translate(-50%, -50%);
    object-fit: cover;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.4); /* 半透明遮罩 */
    z-index: 1;
}

.hero-content {
    position: relative;
    z-index: 2; /* 确保文字在视频和遮罩上方 */
}


.hero-content h1 {
    font-size: 3.5rem;
    margin-bottom: 1rem;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
}

.hero-content p {
    font-size: 1.2rem;
    margin-bottom: 2rem;
    text-shadow: 1px 1px 2px rgba(0,0,0,0.3);
}

.cta-button {
    display: inline-block;
    padding: 1rem 2rem;
    background: linear-gradient(45deg, #FF6B6B, #4ECDC4);
    color: #fff;
    text-decoration: none;
    border-radius: 30px;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(0,0,0,0.2);
}

.cta-button:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(0,0,0,0.3);
}

/* Featured Courses Section */
.featured-courses {
    padding: 5rem 5%;
    background-color: #f9f9f9;
}

.featured-courses h2 {
    text-align: center;
    margin-bottom: 3rem;
    color: #2c3e50;
    font-size: 2.5rem;
    position: relative;
}

.featured-courses h2::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 100px;
    height: 3px;
    background: linear-gradient(45deg, #FF6B6B, #4ECDC4);
}

.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.course-card {
    background: #fff;
    border-radius: 15px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    transition: all 0.3s ease;
}

.course-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.15);
}

.course-card img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    transition: transform 0.3s ease;
}

.course-card:hover img {
    transform: scale(1.05);
}

.course-card h3 {
    padding: 1.5rem 1.5rem 0.5rem;
    color: #2c3e50;
    font-size: 1.5rem;
}

.course-card p {
    padding: 0 1.5rem 1.5rem;
    color: #666;
}

.learn-more {
    display: inline-block;
    padding: 0.8rem 1.5rem;
    margin: 0 1.5rem 1.5rem;
    color: #FF6B6B;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    border: 2px solid #FF6B6B;
    border-radius: 25px;
}

.learn-more:hover {
    background: linear-gradient(45deg, #FF6B6B, #4ECDC4);
    color: #fff;
    border-color: transparent;
}

/* Why Choose Us Section */
.why-choose-us {
    padding: 5rem 5%;
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
}

.why-choose-us h2 {
    text-align: center;
    margin-bottom: 3rem;
    color: #2c3e50;
    font-size: 2.5rem;
    position: relative;
}

.why-choose-us h2::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 100px;
    height: 3px;
    background: linear-gradient(45deg, #FF6B6B, #4ECDC4);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.feature {
    text-align: center;
    padding: 2rem;
    background: #fff;
    border-radius: 15px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    transition: all 0.3s ease;
}

.feature:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.15);
}

.feature i {
    font-size: 2.5rem;
    background: linear-gradient(45deg, #FF6B6B, #4ECDC4);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 1rem;
}

.feature h3 {
    margin-bottom: 1rem;
    color: #2c3e50;
}

/* Footer */
footer {
    background: linear-gradient(135deg, #2c3e50 0%, #3498db 100%);
    color: #fff;
    padding: 3rem 5% 1rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.footer-section h3 {
    margin-bottom: 1rem;
    color: #fff;
    font-size: 1.5rem;
}

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

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: #fff;
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-section a:hover {
    color: #FF6B6B;
}

.footer-bottom {
    text-align: center;
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid rgba(255,255,255,0.1);
}

/* Responsive Design */
@media screen and (max-width: 768px) {
    .nav-links {
        display: none;
    }

    .hamburger {
        display: flex;
    }

    .hero-content h1 {
        font-size: 2.5rem;
    }

    .hero-content p {
        font-size: 1rem;
    }

    .course-grid {
        grid-template-columns: 1fr;
    }

    .features-grid {
        grid-template-columns: 1fr;
    }
}

/* Animation for Mobile Menu */
.nav-links.active {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: #fff;
    padding: 1rem;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.nav-links.active a {
    margin: 0.5rem 0;
}

/* About Page Styles */
.about-hero {
    height: 60vh;
    background: linear-gradient(rgba(0,0,0,0.6), rgba(0,0,0,0.6)), url('../images/about-hero.jpg');
    background-size: cover;
    background-position: center;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: #fff;
    margin-top: 80px;
}

.about-hero-content h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.about-hero-content p {
    font-size: 1.2rem;
}

.about-content {
    padding: 5rem 5%;
    background-color: #f9f9f9;
}

.about-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    max-width: 1200px;
    margin: 0 auto;
}

.about-text h2 {
    color: #2c3e50;
    margin-bottom: 1.5rem;
}

.about-text h3 {
    color: #3498db;
    margin: 2rem 0 1rem;
}

.about-text p {
    color: #666;
    margin-bottom: 1rem;
}

.about-stats {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem;
    align-items: center;
}

.stat-item {
    text-align: center;
    padding: 2rem;
    background: #fff;
    border-radius: 10px;
    box-shadow: 0 3px 10px rgba(0,0,0,0.1);
    transition: transform 0.3s ease;
}

.stat-item:hover {
    transform: translateY(-5px);
}

.stat-item i {
    font-size: 2.5rem;
    color: #3498db;
    margin-bottom: 1rem;
}

.stat-item h3 {
    font-size: 2rem;
    color: #2c3e50;
    margin-bottom: 0.5rem;
}

.stat-item p {
    color: #666;
}

.values-section {
    padding: 5rem 5%;
    background-color: #fff;
}

.values-section h2 {
    text-align: center;
    color: #2c3e50;
    margin-bottom: 3rem;
}

.values-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.value-item {
    text-align: center;
    padding: 2rem;
    background: #f9f9f9;
    border-radius: 10px;
    transition: transform 0.3s ease;
}

.value-item:hover {
    transform: translateY(-5px);
}

.value-item i {
    font-size: 2.5rem;
    color: #3498db;
    margin-bottom: 1rem;
}

.value-item h3 {
    color: #2c3e50;
    margin-bottom: 1rem;
}

.value-item p {
    color: #666;
}

/* Responsive Design */
@media screen and (max-width: 768px) {
    .about-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .about-stats {
        grid-template-columns: 1fr;
    }

    .about-hero-content h1 {
        font-size: 2rem;
    }

    .about-hero-content p {
        font-size: 1rem;
    }

    .values-grid {
        grid-template-columns: 1fr;
    }
}

/* Courses Page Styles */
.courses-hero {
    height: 60vh;
    background: linear-gradient(rgba(0,0,0,0.6), rgba(0,0,0,0.6)), url('../images/courses-hero.jpg');
    background-size: cover;
    background-position: center;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: #fff;
    margin-top: 80px;
}

.courses-hero-content h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.courses-hero-content p {
    font-size: 1.2rem;
}

.course-categories {
    padding: 2rem 5%;
    background-color: #f9f9f9;
}

.teacher-categories {
    padding: 2rem 5%;
    background-color: #f9f9f9;
}

.category-filters {
    display: flex;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 0.8rem 1.5rem;
    border: none;
    background-color: #fff;
    color: #2c3e50;
    border-radius: 5px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: 500;
}

.filter-btn:hover,
.filter-btn.active {
    background-color: #3498db;
    color: #fff;
}

.courses-grid-section {
    padding: 4rem 5%;
    background-color: #fff;
}

.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.course-card {
    background: #fff;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 3px 10px rgba(0,0,0,0.1);
    transition: transform 0.3s ease;
    opacity: 0;
    transform: translateY(20px);
    display: flex;
    flex-direction: column;  /* 竖直排列 */
}

.course-card.animate {
    opacity: 1;
    transform: translateY(0);
}

.course-card:hover {
    transform: translateY(-5px);
}

.course-card img {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.course-content {
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    flex-grow: 1;           /* 占满卡片剩余空间 */
}

.course-content h3 {
    color: #2c3e50;
    margin-bottom: 0.5rem;
}

.course-content p {
    color: #666;
    margin-bottom: 1rem;
}

.course-details {
    display: flex;
    gap: 1rem;
    margin-bottom: 1rem;
    color: #666;
    font-size: 0.66rem;
     margin-top: auto;      /* 推到底部 */
}

.course-details span {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.enroll-btn {
    display: inline-block;
    padding: 0.8rem 1.5rem;
    background-color: #3498db;
    color: #fff;
    text-decoration: none;
    border-radius: 5px;
    transition: background-color 0.3s ease;
    width: 130px;          /* 不要100%，保持原始宽度 */
    margin-top: 1rem;      /* 和 details 保持间距 */
}

.enroll-btn:hover {
    background-color: #2980b9;
}

.course-features {
    padding: 4rem 5%;
    background-color: #f9f9f9;
}

.course-features h2 {
    text-align: center;
    color: #2c3e50;
    margin-bottom: 3rem;
}

/* Responsive Design */
@media screen and (max-width: 768px) {
    .courses-hero-content h1 {
        font-size: 2rem;
    }

    .courses-hero-content p {
        font-size: 1rem;
    }

    .category-filters {
        flex-direction: column;
        align-items: center;
    }

    .filter-btn {
        width: 100%;
        max-width: 200px;
    }

    .courses-grid {
        grid-template-columns: 1fr;
    }

    .course-details {
        flex-direction: column;
        gap: 0.5rem;
    }
}

/* Teachers Page Styles */
.teachers-hero {
    height: 60vh;
    background: linear-gradient(rgba(0,0,0,0.6), rgba(0,0,0,0.6)), url('../images/teachers-hero.jpg');
    background-size: cover;
    background-position: center;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: #fff;
    margin-top: 80px;
}

.teachers-hero-content h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.teachers-hero-content p {
    font-size: 1.2rem;
}

.teachers-grid-section {
    padding: 4rem 5%;
    background-color: #f9f9f9;
}

.teachers-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.teacher-card {
    background: #fff;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 3px 10px rgba(0,0,0,0.1);
    transition: transform 0.3s ease;
    opacity: 0;
    transform: translateY(20px);

    width: 380px;          /* 根据需要调整大小 */
    min-width: 380px;      /* 防止缩小 */
    max-width: 380px;      /* 防止放大 */
    margin: 0 auto;        
}

.teacher-card.animate {
    opacity: 1;
    transform: translateY(0);
}

.teacher-card:hover {
    transform: translateY(-5px);
}

.teacher-image {
    position: relative;
    overflow: hidden;
    height: 300px;
}

.teacher-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.3s ease;
}

.teacher-card:hover .teacher-image img {
    transform: scale(1.05);
}

.teacher-content {
    padding: 1.5rem;
}

.teacher-content h3 {
    color: #2c3e50;
    margin-bottom: 0.5rem;
}

.teacher-content .specialty {
    color: #3498db;
    font-weight: 500;
    margin-bottom: 1rem;
}

.teacher-content .bio {
    color: #666;
    margin-bottom: 1rem;
    line-height: 1.6;
}

.teacher-social {
    display: flex;
    gap: 1rem;
}

.teacher-social a {
    color: #2c3e50;
    font-size: 1.2rem;
    transition: color 0.3s ease;
}

.teacher-social a:hover {
    color: #3498db;
}

.teacher-qualities {
    padding: 4rem 5%;
    background-color: #fff;
}

.teacher-qualities h2 {
    text-align: center;
    color: #2c3e50;
    margin-bottom: 3rem;
}

.qualities-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.quality-item {
    text-align: center;
    padding: 2rem;
    background: #f9f9f9;
    border-radius: 10px;
    transition: transform 0.3s ease;
}

.quality-item:hover {
    transform: translateY(-5px);
}

.quality-item i {
    font-size: 2.5rem;
    color: #3498db;
    margin-bottom: 1rem;
}

.quality-item h3 {
    color: #2c3e50;
    margin-bottom: 1rem;
}

.quality-item p {
    color: #666;
}

/* Responsive Design */
@media screen and (max-width: 768px) {
    .teachers-hero-content h1 {
        font-size: 2rem;
    }

    .teachers-hero-content p {
        font-size: 1rem;
    }

    .teachers-grid {
        grid-template-columns: 1fr;
    }

    .teacher-image {
        height: 250px;
    }

    .qualities-grid {
        grid-template-columns: 1fr;
    }
} 



/* Nav Item 容器 */
.nav-item {
    position: relative;
    display: inline-block;
}

/* 下拉按钮 */
.nav-dropbtn {
    display: inline-block;
    padding: 0.5rem 1rem;
    color: #2c3e50;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
    position: relative;
}

.nav-dropbtn:hover,
.nav-dropbtn.active {
    color: #FF6B6B;
}

/* 一级下拉菜单容器 */
.nav-dropdown-content {
    display: none;
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    min-width: 130px;
    background: #fff;
    border-radius: 5px;
    box-shadow: 0 8px 16px rgba(0,0,0,0.15);
    z-index: 1000;
}

/* 一级下拉菜单项 */
.nav-dropdown-content a {
    display: block;
    padding: 10px 15px;
    margin: 0;
    color: #2c3e50;
    text-decoration: none;
    transition: background 0.3s, color 0.3s;
    position: relative;
    text-align: center;
}

/* 一级下拉悬停 */
.nav-dropdown-content a:hover {
    background: linear-gradient(45deg, #FF6B6B, #4ECDC4);
    color: #fff;
}

/* Subitem 标题样式（Private / Group） */
.nav-subtitle {
    display: block;
    padding: 10px 15px;
    color: #2c3e50;
    font-weight: 600;
    cursor: default;
    text-align: center;
    position: relative;
}

.nav-subtitle i {
    float: right;
    font-size: 0.7rem;
}

/* 二级下拉容器 */
.nav-subdropdown-content {
    display: none;
    position: absolute;
    top: 0;
    left: 100%;
    min-width: 130px;
    background: #fff;
    border-radius: 5px;
    box-shadow: 0 8px 16px rgba(0,0,0,0.15);
    z-index: 1000;
}

/* 二级下拉菜单项 */
.nav-subdropdown-content a {
    display: block;
    padding: 10px 15px;
    color: #2c3e50;
    text-decoration: none;
    text-align: center;
    transition: background 0.3s, color 0.3s;
}

.nav-subdropdown-content a:hover {
    background: linear-gradient(45deg, #FF6B6B, #4ECDC4);
    color: #fff;
}

/* 桌面端悬停显示 */
@media screen and (min-width: 769px) {
    .nav-item:hover .nav-dropdown-content {
        display: block;
    }
    .nav-subitem:hover .nav-subdropdown-content {
        display: block;
    }
}

/* 移动端点击展开（需 JS 配合切换 .active） */
@media screen and (max-width: 768px) {
    .nav-dropdown-content,
    .nav-subdropdown-content {
        position: static;
        box-shadow: none;
        border-radius: 0;
    }
    .nav-dropdown-content.active,
    .nav-subdropdown-content.active {
        display: block;
    }
}




/* Terms 页面单栏文本 */
.terms-text {
    width: 100%;
    max-width: 900px; /* 可根据需求调整 */
    margin: 0 auto;
    padding: 2rem 1rem;
    line-height: 1.7;
}
/* 仅针对 terms-text 下的列表项 */
.terms-text ul {
    list-style-type: disc; /* 保留圆点，也可以用 decimal 变成数字 */
    padding-left: 2rem;    /* 控制缩进宽度 */
    margin-bottom: 1rem;   /* 列表间距，可选 */
}

.terms-text li {
    margin-bottom: 0.5rem; /* 每个 li 的间距 */
}