/* 课程视图样式 */
#lessonView {
  display: flex;
  flex-direction: column;
  height: 100%;
}

.lesson-header {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 20px 32px;
  background: var(--card-bg);
  border-bottom: 1px solid var(--border-color);
}

.btn-back {
  padding: 8px 16px;
  background: transparent;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
}

.btn-back:hover {
  border-color: var(--primary-color);
  color: var(--primary-color);
  background: rgba(99, 102, 241, 0.05);
}

.lesson-header h2 {
  font-size: 20px;
  font-weight: 700;
}

.lesson-content {
  flex: 1;
  overflow-y: auto;
  padding: 32px;
  max-width: 900px;
  margin: 0 auto;
  width: 100%;
}

/* 课程内容卡片 */
.lesson-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 24px;
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow);
  animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.lesson-card h3 {
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 16px;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 8px;
}

.lesson-card h4 {
  font-size: 16px;
  font-weight: 600;
  margin: 16px 0 12px 0;
  color: var(--text-primary);
}

.lesson-card p {
  font-size: 15px;
  line-height: 1.8;
  color: var(--text-secondary);
  margin-bottom: 12px;
}

.lesson-card ul, .lesson-card ol {
  margin: 12px 0;
  padding-left: 24px;
}

.lesson-card li {
  font-size: 15px;
  line-height: 1.8;
  color: var(--text-secondary);
  margin-bottom: 8px;
}

/* 高亮框 */
.highlight-box {
  background: rgba(88, 204, 2, 0.1);
  border-left: 4px solid var(--primary-color);
  padding: 16px;
  border-radius: 8px;
  margin: 16px 0;
}

.highlight-box.info {
  background: rgba(0, 150, 255, 0.1);
  border-left-color: #0096ff;
}

.highlight-box.warning {
  background: rgba(255, 150, 0, 0.1);
  border-left-color: var(--warning-color);
}

/* 代码块 */
.code-block {
  position: relative;
  margin: 16px 0;
}

.code-block-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 16px;
  background: #21252b;
  border-radius: 8px 8px 0 0;
  border-bottom: 1px solid #181a1f;
}

.code-block-lang {
  font-size: 12px;
  color: #abb2bf;
  font-weight: 600;
}

.btn-copy {
  padding: 4px 12px;
  background: transparent;
  border: 1px solid #3e4451;
  border-radius: 4px;
  color: #abb2bf;
  font-size: 12px;
  cursor: pointer;
  transition: var(--transition);
}

.btn-copy:hover {
  background: #3e4451;
  color: white;
}

.code-block pre {
  margin: 0;
  border-radius: 0 0 8px 8px;
}

/* 题目卡片 */
.problem-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 24px;
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow);
}

.problem-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--border-color);
  flex-wrap: wrap;
  gap: 8px;
}

.problem-title {
  font-size: 18px;
  font-weight: 700;
}

.problem-meta {
  display: flex;
  align-items: center;
  gap: 8px;
}

.problem-id {
  padding: 4px 12px;
  background: var(--primary-color);
  color: white;
  border-radius: 16px;
  font-size: 13px;
  font-weight: 600;
}

/* 难度标签 - 与洛谷官方颜色系统一致 */
.problem-difficulty {
  padding: 3px 10px;
  border-radius: 12px;
  font-size: 12px;
  font-weight: 600;
  white-space: nowrap;
}

/* 洛谷官方难度颜色：
   0=未评定(灰), 1=入门(灰), 2=普及-(红), 3=普及(橙), 4=普及+(黄),
   5=提高-(绿), 6=提高(蓝), 7=省选/NOI/CTSC(紫/黑)
*/
.difficulty-0 { background: #f3f4f6; color: #9ca3af; }  /* 未评定 */
.difficulty-1 { background: #f3f4f6; color: #6b7280; }  /* 入门 灰 */
.difficulty-2 { background: #fef2f2; color: #dc2626; }  /* 普及- 红 */
.difficulty-3 { background: #fff7ed; color: #ea580c; }  /* 普及 橙 */
.difficulty-4 { background: #fefce8; color: #ca8a04; }  /* 普及+ 黄 */
.difficulty-5 { background: #f0fdf4; color: #16a34a; }  /* 提高- 绿 */
.difficulty-6 { background: #eff6ff; color: #2563eb; }  /* 提高 蓝 */
.difficulty-7 { background: #f5f3ff; color: #7c3aed; }  /* 省选/NOI 紫 */

/* 题目加载提示 */
.fetch-notice {
  text-align: center;
  padding: 24px 16px;
  background: var(--bg-color);
  border-radius: 12px;
  border: 1px dashed var(--border-color);
}

.fetch-notice p {
  color: var(--text-secondary);
  margin-bottom: 12px;
  font-size: 14px;
}

.btn-retry {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 8px 16px;
  background: var(--primary-color);
  color: white;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
}

.btn-retry:hover {
  opacity: 0.9;
  transform: translateY(-1px);
}

.problem-section {
  margin-bottom: 20px;
}

.problem-section h4 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 12px;
  color: var(--primary-color);
}

.problem-section p {
  font-size: 15px;
  line-height: 1.8;
  color: var(--text-secondary);
}

/* 题目中的图片自适应 */
.problem-section img,
.lesson-content-text img {
  max-width: 100%;
  height: auto;
  border-radius: 6px;
  margin: 12px 0;
  display: block;
}

/* 样例输入输出 */
.sample-block {
  background: var(--bg-color);
  border-radius: 8px;
  padding: 16px;
  margin: 12px 0;
  border: 1px solid var(--border-color);
}

.sample-label {
  font-size: 12px;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 8px;
  text-transform: uppercase;
}

.sample-content {
  font-family: 'Fira Code', 'Consolas', monospace;
  font-size: 14px;
  line-height: 1.6;
  color: var(--text-primary);
  white-space: pre-wrap;
}

/* 思路输入区 */
.thinking-area {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 24px;
  border: 2px solid var(--border-color);
}

.thinking-area h4 {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.thinking-textarea {
  width: 100%;
  min-height: 150px;
  padding: 16px;
  background: var(--bg-color);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  color: var(--text-primary);
  font-size: 15px;
  line-height: 1.6;
  resize: vertical;
  font-family: inherit;
}

.thinking-textarea:focus {
  outline: none;
  border-color: var(--primary-color);
}

.thinking-actions {
  display: flex;
  gap: 12px;
  margin-top: 16px;
}

/* AC 按钮 */
.btn-ac {
  padding: 16px 32px;
  background: linear-gradient(135deg, var(--success-color), #46a302);
  color: white;
  border: none;
  border-radius: var(--radius);
  font-size: 18px;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: 0 6px 0 #3d8b02;
  display: flex;
  align-items: center;
  gap: 8px;
}

.btn-ac:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 0 #3d8b02;
}

.btn-ac:active {
  transform: translateY(2px);
  box-shadow: 0 4px 0 #3d8b02;
}

.btn-ac.completed {
  background: linear-gradient(135deg, var(--accent-color), #ff6b00);
  box-shadow: 0 6px 0 #cc5500;
}

/* AI 回复区 */
.ai-response {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 24px;
  border: 1px solid var(--border-color);
  animation: slideIn 0.5s ease;
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateX(-20px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

.ai-response h4 {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 16px;
  color: var(--primary-color);
  display: flex;
  align-items: center;
  gap: 8px;
}

.ai-response-content {
  font-size: 15px;
  line-height: 1.8;
  color: var(--text-secondary);
}

.ai-response-content p {
  margin-bottom: 12px;
}

.ai-response-content ul, .ai-response-content ol {
  margin: 12px 0;
  padding-left: 24px;
}

.ai-response-content li {
  margin-bottom: 8px;
}

/* 追问输入框 */
.followup-area {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 24px;
  border: 1px solid var(--border-color);
}

.followup-input {
  width: 100%;
  min-height: 80px;
  padding: 12px;
  background: var(--bg-color);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  color: var(--text-primary);
  font-size: 14px;
  line-height: 1.6;
  resize: vertical;
  font-family: inherit;
  margin-bottom: 12px;
}

.followup-input:focus {
  outline: none;
  border-color: var(--primary-color);
}

.followup-actions {
  display: flex;
  gap: 12px;
}

/* 响应式设计 */
@media (max-width: 768px) {
  .lesson-content {
    padding: 20px 16px;
  }
  
  .lesson-card, .problem-card, .thinking-area, .ai-response {
    padding: 16px;
  }
  
  .lesson-card h3 {
    font-size: 18px;
  }
  
  .problem-title {
    font-size: 16px;
  }
  
  .thinking-area h4 {
    font-size: 16px;
  }
  
  .btn-ac {
    padding: 12px 24px;
    font-size: 16px;
  }
}