:root {
    --primary: #7c3aed;
    --primary-dark: #6d28d9;
    --secondary: #8b5cf6;
    --light: #f5f3ff;
    --dark: #1e1b4b;
    --accent: #f59e0b;
    --gray: #64748b;
    --light-gray: #f8fafc;
    --font-family: "Noto Sans SC", "仿宋", "FangSong", serif;
}

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

body {
    font-family: var(--font-family);
    line-height: 1.8;
    color: var(--dark);
    background-color: #ffffff;
}

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

/* 导航栏样式 */
header {
    background: white;
    box-shadow: 0 2px 10px 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 0;
}

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

.logo i {
    margin-right: 0.5rem;
    font-size: 1.8rem;
}

.nav-links {
    display: flex;
    list-style: none;
}

.nav-links li {
    margin-left: 2rem;
}

.nav-links a {
    color: var(--dark);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

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

.nav-links a.active {
    color: var(--primary);
    border-bottom: 2px solid var(--primary);
}

/* 英雄区域样式 */
.hero {
    background: linear-gradient(135deg, var(--light) 0%, #ede9fe 100%);
    padding: 8rem 0 6rem;
    margin-top: 70px;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 100%;
    height: 200%;
    background: radial-gradient(circle, rgba(124, 58, 237, 0.1) 0%, transparent 70%);
    transform: rotate(-15deg);
}

.hero-content {
    text-align: center;
    position: relative;
    z-index: 2;
}

.hero h1 {
    font-size: 3.5rem;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: 1.5rem;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero p {
    font-size: 1.25rem;
    color: var(--gray);
    margin-bottom: 2rem;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.hero-badges {
    display: flex;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
    margin-bottom: 2rem;
}

.badge {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: 25px;
    font-size: 0.9rem;
    font-weight: 500;
    box-shadow: 0 2px 10px rgba(124, 58, 237, 0.3);
}

.hero-actions {
    margin-top: 2rem;
}

.btn {
    display: inline-block;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    color: white;
    padding: 1rem 2rem;
    text-decoration: none;
    border-radius: 50px;
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(124, 58, 237, 0.3);
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(124, 58, 237, 0.4);
}

.btn-outline {
    background: transparent;
    color: var(--primary);
    border: 2px solid var(--primary);
    box-shadow: none;
}

.btn-outline:hover {
    background: var(--primary);
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(124, 58, 237, 0.4);
}

/* 通用区域样式 */
.section {
    padding: 5rem 0;
}

.section-title {
    text-align: center;
    margin-bottom: 4rem;
}

.section-title h2 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: 1rem;
    position: relative;
}

.section-title h2::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 4px;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    border-radius: 2px;
}

.section-title p {
    font-size: 1.1rem;
    color: var(--gray);
    max-width: 600px;
    margin: 0 auto;
}

/* 课程概览样式 */
.overview-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.overview-card {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    text-align: center;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
    border: 1px solid var(--light-gray);
}

.overview-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.15);
    border-color: var(--primary);
}

.overview-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--light) 0%, #ede9fe 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
}

.overview-icon i {
    font-size: 2rem;
    color: var(--primary);
}

.overview-card h3 {
    font-size: 1.3rem;
    font-weight: 600;
    color: var(--dark);
    margin-bottom: 1rem;
}

.overview-card p {
    color: var(--gray);
    line-height: 1.6;
}

/* 竞赛内容样式 */
.contest-section {
    background: white;
    border-radius: 15px;
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.08);
    border: 1px solid var(--light-gray);
    transition: all 0.3s ease;
}

.contest-section:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.12);
}

.contest-header {
    text-align: center;
    margin-bottom: 2rem;
    padding-bottom: 1.5rem;
    border-bottom: 2px solid var(--light-gray);
}

.contest-header h3 {
    font-size: 1.8rem;
    font-weight: 600;
    color: var(--primary);
    margin-bottom: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
}

.contest-header h3 i {
    margin-right: 0.5rem;
    color: var(--accent);
}

.contest-header p {
    color: var(--gray);
    font-size: 1.1rem;
}

.contest-topics {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
}

.topic-card {
    background: var(--light-gray);
    padding: 1.5rem;
    border-radius: 10px;
    border-left: 4px solid var(--primary);
}

.topic-card h4 {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--dark);
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
}

.topic-card h4 i {
    margin-right: 0.5rem;
    color: var(--accent);
}

.topic-card ul {
    list-style: none;
}

.topic-card li {
    color: var(--gray);
    margin-bottom: 0.5rem;
    padding-left: 1.5rem;
    position: relative;
}

.topic-card li::before {
    content: '•';
    color: var(--primary);
    font-weight: bold;
    position: absolute;
    left: 0;
}

/* 学习目标样式 */
.objectives-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.objective-item {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    text-align: center;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
    border: 1px solid var(--light-gray);
}

.objective-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.15);
    border-color: var(--primary);
}

.objective-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--light) 0%, #ede9fe 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
}

.objective-icon i {
    font-size: 2rem;
    color: var(--primary);
}

.objective-item h3 {
    font-size: 1.3rem;
    font-weight: 600;
    color: var(--dark);
    margin-bottom: 1rem;
}

.objective-item p {
    color: var(--gray);
    line-height: 1.6;
}

/* 课程安排样式 */
.schedule-timeline {
    max-width: 800px;
    margin: 0 auto;
    position: relative;
}

.schedule-timeline::before {
    content: '';
    position: absolute;
    left: 50%;
    top: 0;
    bottom: 0;
    width: 4px;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    transform: translateX(-50%);
}

.timeline-item {
    position: relative;
    margin-bottom: 3rem;
    opacity: 0;
    transform: translateY(30px);
    animation: fadeInUp 0.6s ease forwards;
}

.timeline-item:nth-child(1) { animation-delay: 0.1s; }
.timeline-item:nth-child(2) { animation-delay: 0.3s; }
.timeline-item:nth-child(3) { animation-delay: 0.5s; }
.timeline-item:nth-child(4) { animation-delay: 0.7s; }

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

.timeline-item:nth-child(odd) .timeline-content {
    margin-left: 0;
    margin-right: 3rem;
    text-align: right;
}

.timeline-item:nth-child(even) .timeline-content {
    margin-left: 3rem;
    margin-right: 0;
    text-align: left;
}

.timeline-marker {
    position: absolute;
    left: 50%;
    top: 0;
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: 700;
    font-size: 1.2rem;
    transform: translateX(-50%);
    box-shadow: 0 4px 15px rgba(124, 58, 237, 0.3);
    z-index: 2;
}

.timeline-content {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.08);
    border: 1px solid var(--light-gray);
}

.timeline-content h3 {
    font-size: 1.3rem;
    font-weight: 600;
    color: var(--dark);
    margin-bottom: 1rem;
}

.timeline-content p {
    color: var(--gray);
    margin-bottom: 1rem;
}

.timeline-duration {
    display: inline-block;
    background: var(--light);
    color: var(--primary);
    padding: 0.3rem 0.8rem;
    border-radius: 15px;
    font-size: 0.9rem;
    font-weight: 500;
}

/* 页脚样式 */
footer {
    background: var(--dark);
    color: white;
    padding: 3rem 0 1rem;
}

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

.footer-col h3 {
    color: var(--primary);
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

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

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

.footer-col a {
    color: #cbd5e1;
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-col a:hover {
    color: var(--primary);
}

.copyright {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid #374151;
    color: #9ca3af;
}

/* 返回顶部按钮 */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    color: white;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: none;
    font-size: 1.2rem;
    box-shadow: 0 4px 15px rgba(124, 58, 237, 0.3);
    transition: all 0.3s ease;
    z-index: 1000;
    text-align: center;
    line-height: 50px;
}

.back-to-top:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(124, 58, 237, 0.4);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 2.5rem;
    }
    
    .hero p {
        font-size: 1.1rem;
    }
    
    .section-title h2 {
        font-size: 2rem;
    }
    
    .overview-grid,
    .objectives-grid {
        grid-template-columns: 1fr;
    }
    
    .contest-topics {
        grid-template-columns: 1fr;
    }
    
    .schedule-timeline::before {
        left: 20px;
    }
    
    .timeline-marker {
        left: 20px;
        transform: none;
    }
    
    .timeline-item:nth-child(odd) .timeline-content,
    .timeline-item:nth-child(even) .timeline-content {
        margin-left: 3rem;
        margin-right: 0;
        text-align: left;
    }
    
    .nav-links {
        display: none;
    }
    
    .hero-badges {
        flex-direction: column;
        align-items: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 1rem;
    }
    
    .hero {
        padding: 6rem 0 4rem;
    }
    
    .section {
        padding: 3rem 0;
    }
    
    .overview-card,
    .objective-item,
    .timeline-content {
        padding: 1.5rem;
    }
    
    .back-to-top {
        bottom: 20px;
        right: 20px;
        width: 45px;
        height: 45px;
        font-size: 1rem;
        line-height: 45px;
    }
}