/* 通用容器样式 */
.container {
    max-width: 1200px;
    margin: 0 auto;
}

/* 基础重置和通用样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* 全局超链接样式 */
a {
    text-decoration: none;
    color: inherit;
}

a:hover {
    text-decoration: none;
}

body {
    font-family: 'Microsoft YaHei', 'PingFang SC', sans-serif;
    min-height: 100vh;
    padding: 20px;
}

/* 页面头部通用样式 */
.page-header {
    background: white;
    border-radius: 20px;
    padding: 20px;
    margin-bottom: 30px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 15px;
}

.back-btn {
    color: white;
    border: none;
    padding: 12px 25px;
    border-radius: 30px;
    font-size: 1rem;
    font-weight: bold;
    cursor: pointer;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    transition: all 0.3s ease;
}

.subject-title {
    font-size: 2rem;
    font-weight: bold;
    display: flex;
    align-items: center;
    gap: 10px;
}

/* 主要内容区域 */
.content-area {
    background: white;
    border-radius: 20px;
    padding: 40px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    min-height: 500px;
}

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

.welcome-icon {
    font-size: 5rem;
    margin-bottom: 20px;
}

.welcome-text {
    font-size: 2rem;
    font-weight: bold;
    margin-bottom: 15px;
}

.welcome-subtext {
    font-size: 1.2rem;
    color: #666;
}

/* 课程模块通用样式 */
.course-modules {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 25px;
    margin-top: 30px;
}

.module-card {
    border-radius: 15px;
    padding: 25px;
    text-align: center;
    transition: all 0.3s ease;
    border: 2px solid transparent;
    cursor: pointer;
}

/* 可链接的模块卡片 */
.module-card.linkable {
    text-decoration: none;
    display: block;
}

.module-card.linkable:hover {
    text-decoration: none;
}

.module-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.3);
}

.module-icon {
    font-size: 3rem;
    margin-bottom: 15px;
}

.module-title {
    font-size: 1.3rem;
    font-weight: bold;
    margin-bottom: 10px;
}

.module-desc {
    color: #666;
    font-size: 0.95rem;
    line-height: 1.5;
}

/* 通用动画定义 */
@keyframes bounce {
    0%, 20%, 50%, 80%, 100% { transform: translateY(0); }
    40% { transform: translateY(-20px); }
    60% { transform: translateY(-10px); }
}

@keyframes pulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.1); }
    100% { transform: scale(1); }
}

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

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

/* 响应式设计通用规则 */
@media (max-width: 768px) {
    .page-header {
        flex-direction: column;
        text-align: center;
    }
    
    .subject-title {
        font-size: 1.5rem;
    }
    
    .content-area {
        padding: 25px;
    }
    
    .welcome-icon {
        font-size: 3rem;
    }
    
    .welcome-text {
        font-size: 1.5rem;
    }
    
    .course-modules {
        grid-template-columns: 1fr;
        gap: 20px;
    }
}

@media (max-width: 480px) {
    body {
        padding: 15px;
    }
    
    .content-area {
        padding: 20px;
    }
}