/* ===== 基础变量 ===== */
:root {
    /* 蓝绿色系配色 */
    --primary-color: #0d9488;
    --primary-light: #14b8a6;
    --primary-dark: #0f766e;
    --secondary-color: #0ea5e9;
    --accent-color: #06b6d4;
    
    /* 中性色 */
    --bg-color: #f8fafc;
    --bg-secondary: #f1f5f9;
    --text-color: #1e293b;
    --text-secondary: #64748b;
    --text-light: #94a3b8;
    --border-color: #e2e8f0;
    --white: #ffffff;
    
    /* 阴影 */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    
    /* 圆角 */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    
    /* 过渡 */
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
    --transition-slow: 350ms ease;
}

/* ===== 重置样式 ===== */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
}

a {
    text-decoration: none;
    color: inherit;
}

ul {
    list-style: none;
}

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

/* ===== 容器 ===== */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* ===== 导航栏 ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: var(--transition-normal);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 64px;
}

.logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
    transition: var(--transition-fast);
}

.logo:hover {
    color: var(--primary-dark);
}

.nav-links {
    display: flex;
    gap: 2rem;
}

.nav-links a {
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--text-secondary);
    transition: var(--transition-fast);
    position: relative;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: var(--transition-fast);
}

.nav-links a:hover {
    color: var(--primary-color);
}

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

/* ===== 英雄区域 ===== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    background: linear-gradient(135deg, var(--bg-color) 0%, var(--bg-secondary) 100%);
    padding-top: 64px;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 80%;
    height: 150%;
    background: linear-gradient(135deg, rgba(13, 148, 136, 0.05) 0%, rgba(14, 165, 233, 0.05) 100%);
    border-radius: 50%;
    z-index: 0;
}

.hero-content {
    position: relative;
    z-index: 1;
}

.hero h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
    line-height: 1.2;
}

.highlight {
    color: var(--primary-color);
    position: relative;
}

.highlight::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 8px;
    background: linear-gradient(90deg, var(--primary-light), var(--secondary-color));
    opacity: 0.3;
    border-radius: 4px;
}

.subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
}

.school-info {
    font-size: 1rem;
    color: var(--text-light);
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.icon {
    font-size: 1.25rem;
}

.hero-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-top: 1.5rem;
}

.tag {
    display: inline-block;
    padding: 0.5rem 1rem;
    background: var(--white);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    transition: var(--transition-fast);
}

.tag:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

/* ===== 通用区块 ===== */
.section {
    padding: 5rem 0;
}

.section-title {
    font-size: 2rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 1rem;
    color: var(--text-color);
}

.section-desc {
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: 3rem;
}

/* ===== 关于我 ===== */
.about {
    background: var(--white);
}

.about-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

.about-card {
    text-align: center;
    padding: 2rem;
    background: var(--bg-color);
    border-radius: var(--radius-xl);
    transition: var(--transition-normal);
}

.about-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.about-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.about-card h3 {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 0.5rem;
}

.about-card p {
    color: var(--text-secondary);
    font-size: 0.9375rem;
}

/* ===== 课程列表 ===== */
.courses {
    background: var(--bg-secondary);
}

.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: 1.5rem;
}

.course-card {
    background: var(--white);
    border-radius: var(--radius-xl);
    padding: 1.75rem;
    transition: var(--transition-normal);
    border: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
}

.course-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-light);
}

.course-card-placeholder {
    background: linear-gradient(135deg, var(--bg-color) 0%, var(--white) 100%);
    border-style: dashed;
}

.course-card-placeholder:hover {
    border-color: var(--primary-color);
}

.course-icon {
    width: 48px;
    height: 48px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1rem;
}

.course-icon svg {
    width: 24px;
    height: 24px;
    color: var(--white);
}

.course-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 0.75rem;
}

.course-desc {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    line-height: 1.6;
    flex-grow: 1;
    margin-bottom: 1rem;
}

.course-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.course-tag {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    font-size: 0.8125rem;
    color: var(--text-secondary);
}

.course-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--primary-color);
    font-weight: 500;
    font-size: 0.9375rem;
    transition: var(--transition-fast);
    margin-top: auto;
}

.course-link svg {
    width: 16px;
    height: 16px;
    transition: var(--transition-fast);
}

.course-link:hover {
    color: var(--primary-dark);
}

.course-link:hover svg {
    transform: translateX(4px);
}

/* ===== 联系方式 ===== */
.contact {
    background: var(--white);
}

.contact-content {
    text-align: center;
}

.contact-content p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.contact-info {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 2rem;
}

.contact-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    color: var(--text-color);
    font-size: 1rem;
}

.contact-icon {
    font-size: 1.25rem;
}

/* ===== 页脚 ===== */
.footer {
    background: var(--text-color);
    color: var(--white);
    padding: 2rem 0;
    text-align: center;
}

.footer p {
    opacity: 0.9;
    font-size: 0.9375rem;
}

.footer-note {
    opacity: 0.7;
    font-size: 0.875rem;
    margin-top: 0.5rem;
}

/* ===== 响应式设计 ===== */
@media (max-width: 768px) {
    .navbar .container {
        height: 56px;
    }
    
    .nav-links {
        gap: 1rem;
    }
    
    .nav-links a {
        font-size: 0.875rem;
    }
    
    .hero {
        min-height: auto;
        padding: 8rem 0 4rem;
    }
    
    .hero h1 {
        font-size: 2rem;
    }
    
    .subtitle {
        font-size: 1.125rem;
    }
    
    .section {
        padding: 3rem 0;
    }
    
    .section-title {
        font-size: 1.5rem;
    }
    
    .courses-grid {
        grid-template-columns: 1fr;
    }
    
    .about-content {
        grid-template-columns: 1fr;
    }
    
    .contact-info {
        flex-direction: column;
        gap: 1rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 1rem;
    }
    
    .hero h1 {
        font-size: 1.75rem;
    }
    
    .hero-tags {
        gap: 0.5rem;
    }
    
    .tag {
        padding: 0.375rem 0.75rem;
        font-size: 0.8125rem;
    }
    
    .course-card {
        padding: 1.25rem;
    }
}

/* ===== 动画效果 ===== */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.animate-fade-in {
    animation: fadeInUp 0.6s ease forwards;
}

/* ===== 滚动条样式 ===== */
::-webkit-scrollbar {
    width: 8px;
}

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

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

::-webkit-scrollbar-thumb:hover {
    background: var(--text-secondary);
}