/* 页面标题区样式 */
.page-header {
    background-color: #f1f5f9;
    padding: 80px 0 40px;
    margin-top: 70px;
}

.breadcrumbs {
    color: #666;
    margin-bottom: 15px;
    font-size: 0.9rem;
}

.breadcrumbs a {
    color: #666;
}

.breadcrumbs a:hover {
    color: #3498db;
}

.breadcrumbs span {
    margin: 0 8px;
}

.page-header h1 {
    margin-bottom: 10px;
}

.page-header p {
    font-size: 1.2rem;
    color: #666;
    max-width: 800px;
}

/* 课程内容区样式 */
.course-content {
    padding: 60px 0;
}

.course-layout {
    display: flex;
    gap: 30px;
}

.course-sidebar {
    width: 300px;
    flex-shrink: 0;
}

.course-main {
    flex-grow: 1;
}

/* 课程进度样式 */
.course-progress {
    background-color: white;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
    margin-bottom: 30px;
}

.progress-bar {
    height: 8px;
    background-color: #f1f1f1;
    border-radius: 4px;
    margin: 15px 0;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background-color: #3498db;
    border-radius: 4px;
    transition: width 0.5s ease;
}

.progress-text {
    text-align: right;
    font-weight: 600;
    color: #3498db;
}

/* 课程导航样式 */
.course-navigation {
    background-color: white;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
}

.course-navigation ul {
    list-style: none;
}

.course-navigation li {
    margin-bottom: 10px;
}

.course-navigation a {
    display: block;
    padding: 10px 15px;
    border-radius: 4px;
    transition: all 0.3s ease;
}

.course-navigation li.active a {
    background-color: #e8f4fd;
    color: #3498db;
    font-weight: 600;
}

.course-navigation a:hover {
    background-color: #f1f5f9;
    padding-left: 20px;
}

/* 课时内容样式 */
.lesson-content {
    background-color: white;
    padding: 30px;
    border-radius: 8px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
}

.lesson-intro {
    background-color: #f8fafc;
    padding: 20px;
    border-radius: 8px;
    margin-bottom: 30px;
    border-left: 4px solid #3498db;
}

.lesson-section {
    margin-bottom: 40px;
}

.lesson-section p {
    margin-bottom: 15px;
    line-height: 1.7;
}

.custom-list {
    padding-left: 25px;
    margin-bottom: 20px;
}

.custom-list li {
    margin-bottom: 10px;
    position: relative;
    padding-left: 10px;
}

.custom-list li::before {
    content: '•';
    color: #3498db;
    font-weight: bold;
    position: absolute;
    left: -20px;
}

/* 卡片样式 */
.card {
    background-color: #f8fafc;
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 20px;
    border: 1px solid #e2e8f0;
}

.card h4 {
    margin-bottom: 10px;
    color: #2c3e50;
}

/* 示例列表样式 */
.example-list {
    background-color: #f8fafc;
    border-radius: 8px;
    padding: 20px 20px 20px 40px;
    margin: 20px 0;
    border-left: 4px solid #2ecc71;
}

.example-list li {
    margin-bottom: 10px;
}

/* 练习题样式 */
.lesson-exercise {
    background-color: #f8fafc;
    border-radius: 8px;
    padding: 25px;
    margin-top: 40px;
}

.exercise-list {
    padding-left: 20px;
    margin-bottom: 20px;
}

.exercise-list li {
    margin-bottom: 30px;
    padding-bottom: 20px;
    border-bottom: 1px solid #e2e8f0;
}

.exercise-list li:last-child {
    border-bottom: none;
}

.show-answer-btn {
    background-color: transparent;
    color: #3498db;
    border: 1px solid #3498db;
    padding: 5px 15px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.3s ease;
}

.show-answer-btn:hover {
    background-color: #3498db;
    color: white;
}

.answer-content {
    margin-top: 15px;
    padding: 15px;
    background-color: white;
    border-radius: 4px;
    border-left: 3px solid #3498db;
}

/* 课时导航按钮 */
.lesson-navigation {
    display: flex;
    justify-content: space-between;
    margin-top: 40px;
    padding-top: 20px;
    border-top: 1px solid #e2e8f0;
}

.disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.disabled:hover {
    background-color: transparent;
    color: #3498db;
    border-color: #3498db;
}

/* 相关推荐课程 */
.related-courses {
    padding: 60px 0;
    background-color: #f9f9f9;
}

.related-courses .courses-grid {
    margin-top: 30px;
}

/* 响应式设计 */
@media (max-width: 992px) {
    .course-layout {
        flex-direction: column;
    }
    
    .course-sidebar {
        width: 100%;
    }
    
    .course-navigation {
        overflow-x: auto;
    }
    
    .course-navigation ul {
        display: flex;
        gap: 10px;
        min-width: max-content;
    }
    
    .course-navigation li {
        margin-bottom: 0;
    }
    
    .course-navigation a {
        white-space: nowrap;
    }
}

@media (max-width: 768px) {
    .page-header {
        padding: 60px 0 30px;
    }
    
    .lesson-content {
        padding: 20px;
    }
    
    .lesson-exercise {
        padding: 15px;
    }
}