/* ===== 全局重置 ===== */
* { margin: 0; padding: 0; box-sizing: border-box; }

:root {
  --primary: #5B6CFF;
  --primary-light: #7C8AFF;
  --primary-dark: #4454D9;
  --primary-bg: #EEF0FF;
  --primary-glow: rgba(91,108,255,0.25);
  --success: #2DD573;
  --success-bg: #E8FBEF;
  --danger: #FF4757;
  --danger-bg: #FFEAEC;
  --warning: #FFA502;
  --warning-bg: #FFF8E6;
  --bg: #F0F2F8;
  --bg-grad: linear-gradient(135deg, #F0F2F8 0%, #E8EAF2 100%);
  --card-bg: #FFFFFF;
  --card-grad: linear-gradient(180deg, #FFFFFF 0%, #FCFCFF 100%);
  --text: #1A1B2E;
  --text-secondary: #5C5F73;
  --text-tertiary: #A0A3B5;
  --border: #E4E6F0;
  --border-light: #F0F1F6;
  --radius: 14px;
  --radius-sm: 10px;
  --radius-xs: 6px;
  --shadow-sm: 0 1px 3px rgba(26,27,46,0.04), 0 1px 2px rgba(26,27,46,0.06);
  --shadow: 0 2px 8px rgba(26,27,46,0.06), 0 1px 3px rgba(26,27,46,0.04);
  --shadow-md: 0 4px 16px rgba(26,27,46,0.08), 0 2px 6px rgba(26,27,46,0.04);
  --shadow-lg: 0 12px 32px rgba(26,27,46,0.12), 0 4px 12px rgba(26,27,46,0.06);
  --sidebar-grad: linear-gradient(180deg, #2A2E5C 0%, #1E2148 100%);
  --sidebar-w: 250px;
  --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

body {
  font-family: 'Noto Sans SC', -apple-system, 'Segoe UI', sans-serif;
  background: var(--bg-grad);
  color: var(--text);
  height: 100vh;
  overflow: hidden;
  -webkit-font-smoothing: antialiased;
}

#app {
  display: flex;
  height: 100vh;
}

/* ===== 侧边栏 ===== */
.sidebar {
  width: var(--sidebar-w);
  background: var(--sidebar-grad);
  color: #fff;
  display: flex;
  flex-direction: column;
  flex-shrink: 0;
  position: relative;
  z-index: 10;
}

.sidebar::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0; height: 3px;
  background: linear-gradient(90deg, var(--primary-light), var(--primary), #8B5CF6);
  z-index: 1;
}

.logo {
  padding: 22px 20px;
  display: flex;
  align-items: center;
  gap: 12px;
  border-bottom: 1px solid rgba(255,255,255,0.06);
}

.logo-icon {
  font-size: 34px;
  filter: drop-shadow(0 2px 4px rgba(0,0,0,0.2));
}

.logo-text h1 {
  font-size: 19px;
  font-weight: 700;
  letter-spacing: 0.5px;
  background: linear-gradient(135deg, #fff 0%, #C5C8FF 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.logo-text p {
  font-size: 11px;
  color: rgba(255,255,255,0.4);
  margin-top: 3px;
  letter-spacing: 0.5px;
}

.nav-menu {
  flex: 1;
  padding: 18px 12px;
  overflow-y: auto;
}

.nav-menu::-webkit-scrollbar { width: 4px; }
.nav-menu::-webkit-scrollbar-thumb { background: rgba(255,255,255,0.1); border-radius: 2px; }

.nav-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 13px 16px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  color: rgba(255,255,255,0.6);
  transition: all var(--transition);
  margin-bottom: 6px;
  position: relative;
  overflow: hidden;
}

.nav-item::before {
  content: '';
  position: absolute;
  left: 0; top: 50%;
  transform: translateY(-50%);
  width: 3px; height: 0;
  background: var(--primary-light);
  border-radius: 0 3px 3px 0;
  transition: height var(--transition);
}

.nav-item:hover {
  background: rgba(255,255,255,0.05);
  color: rgba(255,255,255,0.9);
}

.nav-item.active {
  background: linear-gradient(135deg, rgba(91,108,255,0.3) 0%, rgba(91,108,255,0.15) 100%);
  color: #fff;
  box-shadow: inset 0 0 0 1px rgba(91,108,255,0.3);
}

.nav-item.active::before {
  height: 60%;
}

.nav-icon {
  font-size: 18px;
  transition: transform var(--transition);
}

.nav-item:hover .nav-icon { transform: scale(1.15); }

.nav-badge {
  margin-left: auto;
  background: rgba(255,255,255,0.1);
  padding: 2px 9px;
  border-radius: 10px;
  font-size: 11px;
  font-weight: 600;
}

.nav-item.active .nav-badge {
  background: rgba(255,255,255,0.2);
}

.sidebar-footer {
  padding: 16px 12px;
  border-top: 1px solid rgba(255,255,255,0.06);
}

.api-status {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  font-size: 12px;
  color: rgba(255,255,255,0.5);
  margin-bottom: 10px;
}

.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--danger);
  flex-shrink: 0;
  transition: all var(--transition);
}

.status-dot.connected {
  background: var(--success);
  box-shadow: 0 0 8px rgba(45,213,115,0.7);
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% { box-shadow: 0 0 8px rgba(45,213,115,0.7); }
  50% { box-shadow: 0 0 14px rgba(45,213,115,0.9); }
}

.settings-btn {
  width: 100%;
  padding: 11px;
  background: rgba(255,255,255,0.05);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: var(--radius-sm);
  color: rgba(255,255,255,0.7);
  font-size: 13px;
  cursor: pointer;
  transition: all var(--transition);
  font-family: inherit;
}

.settings-btn:hover {
  background: rgba(255,255,255,0.1);
  color: #fff;
  border-color: rgba(255,255,255,0.15);
}

/* ===== 主内容区 ===== */
.main-content {
  flex: 1;
  overflow-y: auto;
  position: relative;
}

.main-content::-webkit-scrollbar { width: 6px; }
.main-content::-webkit-scrollbar-track { background: transparent; }
.main-content::-webkit-scrollbar-thumb { background: rgba(26,27,46,0.08); border-radius: 3px; }
.main-content::-webkit-scrollbar-thumb:hover { background: rgba(26,27,46,0.15); }

.view {
  display: none;
  padding: 28px 36px;
  min-height: 100%;
}

.view.active {
  display: block;
  animation: fadeIn 0.35s ease;
}

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

.view-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 28px;
  flex-wrap: wrap;
  gap: 16px;
}

.view-header h2 {
  font-size: 24px;
  font-weight: 700;
  letter-spacing: -0.3px;
}

/* ===== 知识体系 ===== */
.volume-filter {
  display: flex;
  gap: 4px;
  background: var(--card-bg);
  padding: 5px;
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-sm);
}

.filter-btn {
  padding: 7px 18px;
  border: none;
  background: transparent;
  border-radius: var(--radius-xs);
  cursor: pointer;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
  transition: all var(--transition);
}

.filter-btn:hover { color: var(--text); }

.filter-btn.active {
  background: var(--primary);
  color: #fff;
  box-shadow: 0 2px 8px var(--primary-glow);
}

.chapter-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 18px;
}

.chapter-card {
  background: var(--card-grad);
  border-radius: var(--radius);
  padding: 22px;
  box-shadow: var(--shadow);
  cursor: pointer;
  transition: all var(--transition);
  border: 1px solid var(--border-light);
}

.chapter-card:hover {
  border-color: var(--primary-light);
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
}

.chapter-card-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
}

.chapter-icon {
  font-size: 28px;
  width: 50px;
  height: 50px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--primary-bg);
  border-radius: var(--radius-sm);
  transition: transform var(--transition);
}

.chapter-card:hover .chapter-icon { transform: scale(1.1); }

.chapter-card h3 {
  font-size: 15px;
  font-weight: 700;
  flex: 1;
}

.chapter-volume {
  font-size: 11px;
  padding: 3px 10px;
  border-radius: var(--radius-xs);
  background: var(--primary-bg);
  color: var(--primary);
  font-weight: 600;
}

.chapter-sections { list-style: none; }

.chapter-sections li {
  padding: 9px 12px;
  font-size: 13px;
  color: var(--text-secondary);
  border-radius: var(--radius-xs);
  cursor: pointer;
  transition: all 0.15s;
  display: flex;
  align-items: center;
  gap: 8px;
}

.chapter-sections li:hover {
  background: var(--primary-bg);
  color: var(--primary);
  padding-left: 16px;
}

.chapter-sections li::before {
  content: '▸';
  font-size: 12px;
  color: var(--text-tertiary);
}

.chapter-sections li:hover::before { color: var(--primary); }

/* ===== 练习题 ===== */
.practice-controls {
  display: flex;
  gap: 10px;
  align-items: center;
}

.select-control {
  padding: 9px 14px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 13px;
  background: var(--card-bg);
  cursor: pointer;
  outline: none;
  min-width: 120px;
  transition: border-color var(--transition);
  font-family: inherit;
}

.select-control:focus { border-color: var(--primary); }

.btn {
  padding: 9px 20px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: inherit;
  position: relative;
  overflow: hidden;
}

.btn::after {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(255,255,255,0.15);
  opacity: 0;
  transition: opacity var(--transition);
}

.btn:hover::after { opacity: 1; }

.btn-primary {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: #fff;
  box-shadow: 0 2px 8px var(--primary-glow);
}

.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 14px var(--primary-glow);
}

.btn-primary:disabled {
  background: var(--text-tertiary);
  cursor: not-allowed;
  box-shadow: none;
  transform: none;
}

.btn-secondary {
  background: var(--border);
  color: var(--text);
}

.btn-secondary:hover {
  background: var(--border-light);
  background: #DCDEEC;
}

.btn-success {
  background: linear-gradient(135deg, var(--success) 0%, #22AB5C 100%);
  color: #fff;
  box-shadow: 0 2px 8px rgba(45,213,115,0.25);
}

.btn-success:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 14px rgba(45,213,115,0.3);
}

.btn-danger {
  background: linear-gradient(135deg, var(--danger) 0%, #E03444 100%);
  color: #fff;
  box-shadow: 0 2px 8px rgba(255,71,87,0.2);
}

.practice-placeholder {
  text-align: center;
  padding: 80px 20px;
  color: var(--text-tertiary);
}

.big-icon {
  font-size: 56px;
  display: block;
  margin-bottom: 16px;
  filter: drop-shadow(0 4px 12px rgba(0,0,0,0.06));
}

.practice-placeholder p {
  font-size: 15px;
  margin-bottom: 8px;
}

.sub-text {
  font-size: 13px !important;
  color: var(--text-tertiary);
}

/* 题目卡片 */
.quiz-card {
  background: var(--card-grad);
  border-radius: var(--radius);
  padding: 28px 32px;
  box-shadow: var(--shadow-md);
  margin-bottom: 16px;
  border: 1px solid var(--border-light);
}

.quiz-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 18px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--border-light);
}

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

.quiz-type-badge {
  padding: 4px 12px;
  border-radius: var(--radius-xs);
  font-size: 12px;
  font-weight: 600;
}

.quiz-type-badge.选择 { background: var(--primary-bg); color: var(--primary); }
.quiz-type-badge.填空 { background: var(--warning-bg); color: var(--warning); }
.quiz-type-badge.计算 { background: var(--success-bg); color: var(--success); }

.quiz-difficulty { font-size: 12px; color: var(--text-tertiary); }

.quiz-number {
  font-size: 13px;
  font-weight: 700;
  color: var(--text-secondary);
  padding: 4px 12px;
  background: var(--border-light);
  border-radius: 20px;
}

.quiz-question {
  font-size: 16px;
  line-height: 1.8;
  margin-bottom: 20px;
  font-weight: 500;
}

/* 选择题选项 */
.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.quiz-option {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 13px 18px;
  border: 2px solid var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition);
  font-size: 14px;
  line-height: 1.6;
  user-select: none;
}

.quiz-option:hover {
  border-color: var(--primary-light);
  background: var(--primary-bg);
  transform: translateX(4px);
}

.quiz-option.selected {
  border-color: var(--primary);
  background: var(--primary-bg);
}

.quiz-option.correct {
  border-color: var(--success);
  background: var(--success-bg);
}

.quiz-option.wrong {
  border-color: var(--danger);
  background: var(--danger-bg);
}

/* 锁定状态：提交后不可修改 */
.quiz-option.locked {
  cursor: default;
}

.quiz-option.locked:hover {
  transform: none;
  border-color: inherit;
  background: inherit;
}

.quiz-option.locked.correct:hover {
  border-color: var(--success);
  background: var(--success-bg);
}

.quiz-option.locked.wrong:hover {
  border-color: var(--danger);
  background: var(--danger-bg);
}

.quiz-option.locked:not(.correct):not(.wrong):hover {
  border-color: var(--border);
  background: transparent;
  transform: none;
}

.option-label {
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background: var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 13px;
  flex-shrink: 0;
  transition: all var(--transition);
}

.quiz-option.selected .option-label,
.quiz-option.correct .option-label {
  background: #fff;
}

.quiz-option.correct .option-label {
  color: var(--success);
  border: 2px solid var(--success);
}

.quiz-option.wrong .option-label {
  color: var(--danger);
  border: 2px solid var(--danger);
  background: #fff;
}

/* 填空/计算题输入 */
.quiz-input {
  width: 100%;
  padding: 13px 16px;
  border: 2px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-family: inherit;
  outline: none;
  transition: border-color var(--transition);
  resize: vertical;
  min-height: 60px;
  line-height: 1.6;
}

.quiz-input:focus { border-color: var(--primary); }
.quiz-input.correct { border-color: var(--success); background: var(--success-bg); }
.quiz-input.wrong { border-color: var(--danger); background: var(--danger-bg); }
.quiz-input:read-only { cursor: default; opacity: 0.95; }

/* 批改结果 */
.quiz-result {
  margin-top: 16px;
  padding: 18px;
  border-radius: var(--radius-sm);
  display: none;
  animation: fadeIn 0.35s ease;
}

.quiz-result.show { display: block; }

.quiz-result.correct {
  background: var(--success-bg);
  border-left: 4px solid var(--success);
}

.quiz-result.wrong {
  background: var(--danger-bg);
  border-left: 4px solid var(--danger);
}

.quiz-result.ai-graded {
  background: var(--primary-bg);
  border-left: 4px solid var(--primary);
}

.result-header {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  margin-bottom: 10px;
  font-size: 15px;
}

.result-header.correct { color: var(--success); }
.result-header.wrong { color: var(--danger); }
.result-header.ai-graded { color: var(--primary); }

.result-body {
  font-size: 13px;
  line-height: 1.8;
  color: var(--text);
}

.result-body strong { font-weight: 700; }

.result-score {
  display: inline-block;
  padding: 3px 12px;
  border-radius: var(--radius-xs);
  font-size: 13px;
  font-weight: 700;
  margin-left: 8px;
}

.result-score.good { background: var(--success); color: #fff; }
.result-score.mid { background: var(--warning); color: #fff; }
.result-score.bad { background: var(--danger); color: #fff; }

/* 题目导航 */
.quiz-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 22px;
  padding-top: 18px;
  border-top: 1px solid var(--border-light);
}

.quiz-progress {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-secondary);
}

/* 提交后操作按钮区域 */
.quiz-actions {
  display: flex;
  justify-content: center;
  gap: 10px;
  margin-top: 18px;
}

.quiz-locked-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 16px;
  background: var(--border-light);
  border-radius: 20px;
  font-size: 12px;
  font-weight: 600;
  color: var(--text-tertiary);
  margin-left: auto;
}

/* ===== AI私教对话 ===== */
.tutor-status .model-badge {
  padding: 5px 14px;
  background: var(--primary-bg);
  color: var(--primary);
  border-radius: var(--radius-xs);
  font-size: 12px;
  font-weight: 600;
  border: 1px solid rgba(91,108,255,0.15);
}

.chat-container {
  display: flex;
  flex-direction: column;
  height: calc(100vh - 130px);
  background: var(--card-grad);
  border-radius: var(--radius);
  box-shadow: var(--shadow-md);
  overflow: hidden;
  border: 1px solid var(--border-light);
}

.chat-messages {
  flex: 1;
  overflow-y: auto;
  padding: 28px;
}

.chat-messages::-webkit-scrollbar { width: 5px; }
.chat-messages::-webkit-scrollbar-thumb { background: rgba(26,27,46,0.1); border-radius: 3px; }

.chat-welcome {
  text-align: center;
  padding: 50px 20px;
}

.chat-welcome h3 {
  font-size: 22px;
  margin: 18px 0 10px;
  font-weight: 700;
}

.chat-welcome > p {
  color: var(--text-secondary);
  font-size: 14px;
  margin-bottom: 24px;
}

.chat-suggestions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  justify-content: center;
  max-width: 600px;
  margin: 0 auto;
}

.chat-suggestions button {
  padding: 9px 18px;
  background: var(--primary-bg);
  border: 1px solid transparent;
  border-radius: 22px;
  font-size: 13px;
  color: var(--primary);
  cursor: pointer;
  transition: all var(--transition);
  font-family: inherit;
  font-weight: 500;
}

.chat-suggestions button:hover {
  background: var(--primary);
  color: #fff;
  transform: translateY(-2px);
  box-shadow: 0 4px 12px var(--primary-glow);
}

/* 消息气泡 */
.message {
  display: flex;
  gap: 12px;
  margin-bottom: 22px;
  animation: fadeIn 0.35s ease;
}

.message.user { flex-direction: row-reverse; }

.message-avatar {
  width: 38px;
  height: 38px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  flex-shrink: 0;
}

.message.user .message-avatar {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
}

.message.ai .message-avatar {
  background: var(--success-bg);
}

.message-bubble {
  max-width: 70%;
  padding: 13px 18px;
  border-radius: var(--radius);
  font-size: 14px;
  line-height: 1.8;
}

.message.user .message-bubble {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: #fff;
  border-bottom-right-radius: 4px;
  box-shadow: 0 2px 8px var(--primary-glow);
}

.message.ai .message-bubble {
  background: var(--card-bg);
  color: var(--text);
  border-bottom-left-radius: 4px;
  border: 1px solid var(--border-light);
  box-shadow: var(--shadow-sm);
}

.message-bubble pre {
  background: #1a1b2e;
  color: #e5e7eb;
  padding: 14px;
  border-radius: var(--radius-xs);
  overflow-x: auto;
  font-size: 13px;
  margin: 8px 0;
}

.message-bubble code {
  background: rgba(0,0,0,0.06);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 13px;
}

.message.user .message-bubble code {
  background: rgba(255,255,255,0.2);
}

/* 思考过程折叠 */
.reasoning-toggle {
  margin-top: 10px;
  font-size: 12px;
  color: var(--text-tertiary);
  cursor: pointer;
  user-select: none;
}

.reasoning-toggle:hover { color: var(--primary); }

.reasoning-content {
  display: none;
  margin-top: 8px;
  padding: 12px;
  background: rgba(91,108,255,0.05);
  border-left: 3px solid var(--primary-light);
  border-radius: var(--radius-xs);
  font-size: 13px;
  line-height: 1.7;
  color: var(--text-secondary);
  white-space: pre-wrap;
}

.reasoning-content.show { display: block; }

/* 加载动画 */
.message.loading .message-bubble {
  display: flex;
  gap: 4px;
  align-items: center;
}

.loading-dots {
  display: flex;
  gap: 5px;
}

.loading-dots span {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--text-tertiary);
  animation: bounce 1.4s infinite ease-in-out both;
}

.loading-dots span:nth-child(1) { animation-delay: -0.32s; }
.loading-dots span:nth-child(2) { animation-delay: -0.16s; }

@keyframes bounce {
  0%, 80%, 100% { transform: scale(0.6); opacity: 0.5; }
  40% { transform: scale(1); opacity: 1; }
}

/* 输入区域 */
.chat-input-area {
  padding: 16px 24px;
  border-top: 1px solid var(--border-light);
  background: rgba(255,255,255,0.5);
}

.chat-input-wrapper {
  display: flex;
  gap: 10px;
  align-items: flex-end;
}

.chat-input-wrapper textarea {
  flex: 1;
  padding: 11px 16px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-family: inherit;
  outline: none;
  resize: none;
  max-height: 120px;
  transition: border-color var(--transition);
  line-height: 1.6;
}

.chat-input-wrapper textarea:focus { border-color: var(--primary); }

.btn-send {
  padding: 11px 22px;
  white-space: nowrap;
}

.chat-hint {
  font-size: 11px;
  color: var(--text-tertiary);
  margin-top: 8px;
  text-align: right;
}

/* ===== 学习统计 ===== */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(210px, 1fr));
  gap: 16px;
  margin-bottom: 24px;
}

.stat-card {
  background: var(--card-grad);
  border-radius: var(--radius);
  padding: 22px;
  display: flex;
  align-items: center;
  gap: 16px;
  box-shadow: var(--shadow);
  border: 1px solid var(--border-light);
  transition: transform var(--transition);
}

.stat-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); }

/* 累计完成数高亮卡片 */
.stat-card-highlight {
  background: linear-gradient(135deg, #FFF5E6 0%, #FFF0E0 100%);
  border-color: rgba(255,165,2,0.3);
}

.stat-card-highlight .stat-icon {
  background: rgba(255,165,2,0.12);
  animation: pulse-glow 2s infinite;
}

.stat-card-highlight .stat-value {
  background: linear-gradient(135deg, #FFA502 0%, #FF7F00 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

@keyframes pulse-glow {
  0%, 100% { box-shadow: 0 0 0 0 rgba(255,165,2,0.3); }
  50% { box-shadow: 0 0 0 6px rgba(255,165,2,0); }
}

.stat-icon {
  font-size: 32px;
  width: 58px;
  height: 58px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--primary-bg);
  border-radius: var(--radius-sm);
}

.stat-info {
  display: flex;
  flex-direction: column;
}

.stat-value {
  font-size: 30px;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.5px;
}

.stat-label {
  font-size: 13px;
  color: var(--text-secondary);
  margin-top: 2px;
}

.chapter-progress {
  background: var(--card-grad);
  border-radius: var(--radius);
  padding: 26px;
  box-shadow: var(--shadow);
  border: 1px solid var(--border-light);
}

.chapter-progress h3 {
  font-size: 16px;
  margin-bottom: 18px;
  font-weight: 700;
}

.progress-item {
  margin-bottom: 16px;
}

.progress-item-header {
  display: flex;
  justify-content: space-between;
  font-size: 13px;
  margin-bottom: 7px;
}

.progress-item-title { font-weight: 600; }

.progress-bar {
  height: 10px;
  background: var(--border-light);
  border-radius: 5px;
  overflow: hidden;
  position: relative;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary) 0%, var(--primary-light) 100%);
  border-radius: 5px;
  transition: width 0.6s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
}

.progress-fill::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, transparent 0%, rgba(255,255,255,0.3) 50%, transparent 100%);
  animation: shimmer 2s infinite;
}

@keyframes shimmer {
  0% { transform: translateX(-100%); }
  100% { transform: translateX(100%); }
}

.progress-fill.complete {
  background: linear-gradient(90deg, var(--success) 0%, #44D77F 100%);
}

/* ===== 弹窗 ===== */
.modal-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(30,33,72,0.5);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  z-index: 1000;
  justify-content: center;
  align-items: center;
  animation: fadeIn 0.2s ease;
}

.modal-overlay.show { display: flex; }

.modal {
  background: var(--card-bg);
  border-radius: var(--radius);
  width: 90%;
  max-width: 480px;
  max-height: 90vh;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-lg);
  animation: slideUp 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.modal-large { max-width: 720px; }

@keyframes slideUp {
  from { transform: translateY(24px) scale(0.98); opacity: 0; }
  to { transform: translateY(0) scale(1); opacity: 1; }
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px 24px;
  border-bottom: 1px solid var(--border-light);
}

.modal-header h3 {
  font-size: 18px;
  font-weight: 700;
}

.modal-close {
  border: none;
  background: transparent;
  font-size: 20px;
  cursor: pointer;
  color: var(--text-tertiary);
  padding: 4px 8px;
  border-radius: var(--radius-xs);
  transition: all var(--transition);
  line-height: 1;
}

.modal-close:hover {
  background: var(--bg);
  color: var(--text);
}

.modal-body {
  padding: 24px;
  overflow-y: auto;
  flex: 1;
}

.modal-footer {
  padding: 16px 24px;
  border-top: 1px solid var(--border-light);
  display: flex;
  justify-content: flex-end;
  gap: 10px;
}

.form-group { margin-bottom: 20px; }

.form-group label {
  display: block;
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 8px;
}

.form-input {
  width: 100%;
  padding: 11px 14px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-family: inherit;
  outline: none;
  transition: border-color var(--transition);
}

.form-input:focus { border-color: var(--primary); }

.form-hint {
  font-size: 12px;
  color: var(--text-tertiary);
  margin-top: 8px;
}

.form-hint a { color: var(--primary); }

.model-info {
  display: flex;
  align-items: center;
  gap: 10px;
}

.model-tag {
  padding: 4px 12px;
  background: var(--success-bg);
  color: var(--success);
  border-radius: var(--radius-xs);
  font-size: 12px;
  font-weight: 600;
  font-family: monospace;
}

.model-desc {
  font-size: 13px;
  color: var(--text-secondary);
}

.feature-list {
  list-style: none;
  padding: 0;
}

.feature-list li {
  padding: 9px 0;
  font-size: 13px;
  color: var(--text-secondary);
  border-bottom: 1px solid var(--border-light);
}

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

/* 知识点详情 */
.kp-section { margin-bottom: 22px; }

.kp-section h4 {
  font-size: 15px;
  font-weight: 700;
  margin-bottom: 10px;
  color: var(--primary);
}

.kp-list {
  list-style: none;
  padding-left: 0;
}

.kp-list li {
  padding: 9px 14px;
  font-size: 14px;
  line-height: 1.8;
  background: var(--bg);
  border-radius: var(--radius-xs);
  margin-bottom: 6px;
  border-left: 3px solid var(--primary-light);
}

.kp-formula {
  padding: 14px;
  background: #1a1b2e;
  color: #7DD3FC;
  border-radius: var(--radius-xs);
  font-family: 'Courier New', monospace;
  font-size: 13px;
  margin-bottom: 6px;
  overflow-x: auto;
}

.kp-formula::before { content: '\1F4D0 '; }

.kp-note {
  padding: 11px 14px;
  background: var(--warning-bg);
  border-radius: var(--radius-xs);
  font-size: 13px;
  color: var(--text);
  margin-bottom: 6px;
  border-left: 3px solid var(--warning);
}

.kp-note::before { content: '\1F4A1 '; }

/* AI 讲解区域 */
.ai-explanation {
  margin-top: 20px;
  padding: 18px;
  background: var(--primary-bg);
  border-radius: var(--radius-sm);
  display: none;
}

.ai-explanation.show {
  display: block;
  animation: fadeIn 0.3s ease;
}

.ai-explanation-header {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 12px;
  font-size: 15px;
}

.ai-explanation-content {
  font-size: 14px;
  line-height: 1.9;
  color: var(--text);
  white-space: pre-wrap;
}

/* ===== Toast ===== */
.toast-container {
  position: fixed;
  top: 24px;
  right: 24px;
  z-index: 2000;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.toast {
  padding: 13px 22px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 500;
  box-shadow: var(--shadow-lg);
  animation: slideInRight 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  display: flex;
  align-items: center;
  gap: 8px;
  max-width: 360px;
}

@keyframes slideInRight {
  from { transform: translateX(120%); opacity: 0; }
  to { transform: translateX(0); opacity: 1; }
}

.toast.success { background: linear-gradient(135deg, var(--success) 0%, #22AB5C 100%); color: #fff; }
.toast.error { background: linear-gradient(135deg, var(--danger) 0%, #E03444 100%); color: #fff; }
.toast.info { background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%); color: #fff; }
.toast.warning { background: linear-gradient(135deg, var(--warning) 0%, #E09200 100%); color: #fff; }

/* ===== 填空题内嵌输入框 ===== */
.quiz-question-inline {
  font-size: 16px;
  line-height: 2.6;
  margin-bottom: 20px;
  font-weight: 500;
}

.blank-input {
  display: inline-block;
  border: none;
  border-bottom: 2px solid var(--primary);
  background: var(--primary-bg);
  border-radius: 4px 4px 0 0;
  padding: 3px 12px;
  font-size: 15px;
  font-family: inherit;
  outline: none;
  min-width: 90px;
  text-align: center;
  margin: 0 3px;
  transition: all var(--transition);
  color: var(--text);
}

.blank-input:focus {
  background: #fff;
  border-bottom-width: 3px;
  border-bottom-color: var(--primary-dark);
  box-shadow: 0 2px 8px var(--primary-glow);
}

.blank-input.correct {
  border-bottom-color: var(--success);
  background: var(--success-bg);
  color: var(--success);
  font-weight: 600;
}

.blank-input.wrong {
  border-bottom-color: var(--danger);
  background: var(--danger-bg);
  color: var(--danger);
  font-weight: 600;
}

.blank-input.show-answer {
  border-bottom-color: var(--success);
  background: var(--success-bg);
  color: var(--success);
  font-weight: 600;
}

.blank-input[readonly] {
  cursor: default;
  opacity: 0.95;
}

/* ===== 考试试卷模式 ===== */
.exam-paper {
  background: var(--card-grad);
  border-radius: var(--radius);
  padding: 36px 44px;
  box-shadow: var(--shadow-md);
  max-width: 840px;
  margin: 0 auto;
  border: 1px solid var(--border-light);
}

.exam-header {
  text-align: center;
  margin-bottom: 28px;
  padding-bottom: 22px;
  border-bottom: 2px solid var(--border);
}

.exam-title {
  font-size: 26px;
  font-weight: 700;
  margin-bottom: 10px;
  letter-spacing: 1px;
}

.exam-info {
  font-size: 13px;
  color: var(--text-secondary);
  display: flex;
  justify-content: center;
  gap: 24px;
  flex-wrap: wrap;
}

.exam-info span {
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.exam-section {
  margin-bottom: 32px;
}

.exam-section-title {
  font-size: 16px;
  font-weight: 700;
  margin-bottom: 18px;
  padding: 11px 18px;
  background: var(--primary-bg);
  border-radius: var(--radius-sm);
  border-left: 4px solid var(--primary);
  color: var(--primary);
}

.exam-question {
  margin-bottom: 22px;
  padding: 18px 20px;
  border: 1.5px solid var(--border-light);
  border-radius: var(--radius-sm);
  background: #fff;
  transition: all var(--transition);
}

.exam-question.graded {
  border-color: var(--border);
}

.exam-question.graded.correct {
  border-left: 4px solid var(--success);
  background: linear-gradient(90deg, var(--success-bg) 0%, #fff 8%);
}

.exam-question.graded.wrong {
  border-left: 4px solid var(--danger);
  background: linear-gradient(90deg, var(--danger-bg) 0%, #fff 8%);
}

.exam-question-text {
  font-size: 15px;
  line-height: 2.4;
  margin-bottom: 14px;
  font-weight: 500;
}

.exam-question-num {
  font-weight: 700;
  color: var(--primary);
  margin-right: 6px;
}

.exam-question-inline {
  font-size: 15px;
  line-height: 2.6;
  margin-bottom: 14px;
  font-weight: 500;
}

.exam-options {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-left: 26px;
}

.exam-option {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  padding: 9px 14px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-xs);
  cursor: pointer;
  font-size: 14px;
  line-height: 1.6;
  transition: all var(--transition);
  user-select: none;
}

.exam-option:hover {
  border-color: var(--primary-light);
  background: var(--primary-bg);
}

.exam-option.selected {
  border-color: var(--primary);
  background: var(--primary-bg);
}

.exam-option.correct {
  border-color: var(--success);
  background: var(--success-bg);
}

.exam-option.wrong {
  border-color: var(--danger);
  background: var(--danger-bg);
}

.exam-option.locked { cursor: default; }
.exam-option.locked:hover {
  border-color: inherit;
  background: inherit;
  transform: none;
}

.exam-option-label {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 12px;
  flex-shrink: 0;
  transition: all var(--transition);
}

.exam-option.selected .exam-option-label {
  background: var(--primary);
  color: #fff;
}

.exam-option.correct .exam-option-label {
  background: var(--success);
  color: #fff;
}

.exam-option.wrong .exam-option-label {
  background: var(--danger);
  color: #fff;
}

.exam-calc-input {
  width: calc(100% - 26px);
  margin-left: 26px;
  padding: 12px 16px;
  border: 2px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-family: inherit;
  outline: none;
  min-height: 80px;
  resize: vertical;
  transition: border-color var(--transition);
  line-height: 1.6;
}

.exam-calc-input:focus { border-color: var(--primary); }
.exam-calc-input.correct { border-color: var(--success); background: var(--success-bg); }
.exam-calc-input.wrong { border-color: var(--danger); background: var(--danger-bg); }
.exam-calc-input:disabled { cursor: default; opacity: 0.95; }

.exam-result-inline {
  margin-top: 10px;
  margin-left: 26px;
  padding: 10px 14px;
  border-radius: var(--radius-xs);
  font-size: 13px;
  line-height: 1.8;
  display: none;
  animation: fadeIn 0.3s ease;
}

.exam-result-inline.show { display: block; }
.exam-result-inline.correct {
  background: var(--success-bg);
  border-left: 3px solid var(--success);
}
.exam-result-inline.wrong {
  background: var(--danger-bg);
  border-left: 3px solid var(--danger);
}
.exam-result-inline.ai-graded {
  background: var(--primary-bg);
  border-left: 3px solid var(--primary);
}

.exam-submit-bar {
  text-align: center;
  padding: 28px 0;
  margin-top: 18px;
  border-top: 2px solid var(--border);
}

.exam-score-summary {
  background: linear-gradient(135deg, var(--primary-bg) 0%, rgba(91,108,255,0.03) 100%);
  border-radius: var(--radius);
  padding: 28px;
  text-align: center;
  margin-bottom: 28px;
  display: none;
  border: 1px solid rgba(91,108,255,0.12);
}

.exam-score-summary.show {
  display: block;
  animation: fadeIn 0.4s ease;
}

.exam-score-summary h3 {
  font-size: 18px;
  margin-bottom: 14px;
  color: var(--primary);
}

.exam-score-value {
  font-size: 48px;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 10px;
  letter-spacing: -1px;
}

.exam-score-detail {
  font-size: 14px;
  color: var(--text-secondary);
  display: flex;
  justify-content: center;
  gap: 28px;
  flex-wrap: wrap;
}

.exam-score-detail span strong {
  color: var(--text);
  font-size: 18px;
}

/* ===== 预置试卷卡片 ===== */
.exam-papers-title {
  text-align: center;
  margin: 24px 0 28px;
}

.exam-papers-title h3 {
  font-size: 22px;
  margin-bottom: 6px;
  font-weight: 700;
}

.exam-papers-title p {
  font-size: 13px;
  color: var(--text-tertiary);
}

.exam-paper-cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 16px;
  max-width: 820px;
  margin: 0 auto;
}

.exam-paper-card {
  background: var(--card-grad);
  border-radius: var(--radius);
  padding: 22px;
  box-shadow: var(--shadow);
  cursor: pointer;
  transition: all var(--transition);
  border: 1px solid var(--border-light);
  position: relative;
  overflow: hidden;
}

.exam-paper-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0; height: 4px;
  background: linear-gradient(90deg, var(--primary) 0%, var(--primary-light) 50%, #8B5CF6 100%);
  opacity: 0.8;
  transition: opacity var(--transition);
}

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

.exam-paper-card:hover::before { opacity: 1; }

.exam-paper-card-header {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 16px;
}

.exam-paper-card-icon {
  font-size: 32px;
  width: 54px;
  height: 54px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--primary-bg);
  border-radius: var(--radius-sm);
  flex-shrink: 0;
  transition: transform var(--transition);
}

.exam-paper-card:hover .exam-paper-card-icon { transform: scale(1.1); }

.exam-paper-card-title {
  font-size: 16px;
  font-weight: 700;
  line-height: 1.4;
}

.exam-paper-card-sub {
  font-size: 12px;
  color: var(--text-secondary);
  margin-top: 3px;
}

.exam-paper-card-info {
  display: flex;
  gap: 16px;
  font-size: 13px;
  color: var(--text-secondary);
  flex-wrap: wrap;
}

.exam-paper-card-info span {
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

/* ===== 错题本 ===== */
.wrong-notebook {
  background: var(--card-grad);
  border-radius: var(--radius);
  padding: 26px;
  box-shadow: var(--shadow);
  margin-top: 24px;
  border: 1px solid var(--border-light);
}

.wrong-notebook-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 18px;
  flex-wrap: wrap;
  gap: 8px;
}

.wrong-notebook-header h3 {
  font-size: 17px;
  font-weight: 700;
}

.wrong-notebook-actions {
  display: flex;
  gap: 8px;
}

.btn-sm {
  padding: 7px 16px;
  font-size: 13px;
}

.wrong-notebook-stats { margin-bottom: 18px; }

.wrong-stats-row {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  padding: 13px 18px;
  background: var(--danger-bg);
  border-radius: var(--radius-sm);
  font-size: 13px;
}

.wrong-stat-item strong {
  color: var(--danger);
  font-weight: 700;
}

.wrong-question-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.wrong-empty {
  text-align: center;
  padding: 40px 20px;
  color: var(--text-tertiary);
}

.wrong-empty .big-icon { font-size: 48px; }

.wrong-empty p {
  font-size: 14px;
  margin-top: 8px;
}

.wrong-question-card {
  background: var(--bg);
  border-radius: var(--radius-sm);
  padding: 18px 20px;
  border-left: 4px solid var(--danger);
  transition: transform var(--transition);
}

.wrong-question-card:hover {
  transform: translateX(3px);
}

.wrong-question-header {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 10px;
  flex-wrap: wrap;
}

.wrong-question-badge {
  padding: 3px 10px;
  border-radius: var(--radius-xs);
  font-size: 11px;
  font-weight: 600;
  background: var(--primary-bg);
  color: var(--primary);
}

.wrong-chapter-name {
  font-size: 12px;
  color: var(--text-secondary);
}

.wrong-count-badge {
  padding: 3px 10px;
  border-radius: var(--radius-xs);
  font-size: 11px;
  font-weight: 600;
  background: var(--danger-bg);
  color: var(--danger);
  margin-left: auto;
}

.wrong-question-text {
  font-size: 14px;
  line-height: 1.8;
  margin-bottom: 10px;
  font-weight: 500;
}

.wrong-answer-row {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 8px;
}

.wrong-your-answer {
  font-size: 13px;
  color: var(--danger);
  background: var(--danger-bg);
  padding: 5px 12px;
  border-radius: var(--radius-xs);
}

.wrong-correct-answer {
  font-size: 13px;
  color: var(--success);
  background: var(--success-bg);
  padding: 5px 12px;
  border-radius: var(--radius-xs);
}

.wrong-explanation {
  font-size: 13px;
  line-height: 1.7;
  color: var(--text-secondary);
  padding: 9px 14px;
  background: var(--card-bg);
  border-radius: var(--radius-xs);
  border-left: 2px solid var(--warning);
}

/* ===== 题型切换栏 ===== */
.quiz-type-switcher {
  display: flex;
  gap: 0;
  background: var(--bg);
  border-radius: var(--radius-sm);
  padding: 4px;
  margin-bottom: 16px;
}

.type-switch-btn {
  flex: 1;
  padding: 8px 12px;
  border: none;
  background: transparent;
  border-radius: var(--radius-xs);
  cursor: pointer;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
  transition: all var(--transition);
  font-family: inherit;
  text-align: center;
}

.type-switch-btn:hover {
  color: var(--text);
  background: rgba(255,255,255,0.5);
}

.type-switch-btn.active {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: #fff;
  box-shadow: 0 2px 8px var(--primary-glow);
}

/* ===== 响应式 ===== */
@media (max-width: 768px) {
  .sidebar {
    width: 64px;
  }
  .logo-text, .nav-item span:not(.nav-icon), .nav-badge, .sidebar-footer .api-status span:last-child, .settings-btn {
    display: none;
  }
  .nav-item {
    justify-content: center;
  }
  .view {
    padding: 16px;
  }
  .chapter-grid {
    grid-template-columns: 1fr;
  }
  .practice-controls {
    flex-direction: column;
    align-items: stretch;
  }
  .message-bubble {
    max-width: 85%;
  }
  .quiz-card {
    padding: 18px 16px;
  }
  .exam-paper {
    padding: 20px 16px;
  }
}