/* ===== 基础重置 ===== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --primary: #2563eb;
  --primary-light: #dbeafe;
  --primary-dark: #1d4ed8;
  --green: #16a34a;
  --green-light: #dcfce7;
  --red: #dc2626;
  --red-light: #fee2e2;
  --yellow: #d97706;
  --yellow-light: #fef3c7;
  --purple: #7c3aed;
  --purple-light: #ede9fe;
  --gray-50: #f9fafb;
  --gray-100: #f3f4f6;
  --gray-200: #e5e7eb;
  --gray-300: #d1d5db;
  --gray-400: #9ca3af;
  --gray-500: #6b7280;
  --gray-600: #4b5563;
  --gray-700: #374151;
  --gray-800: #1f2937;
  --gray-900: #111827;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.07), 0 2px 4px rgba(0,0,0,0.04);
  --shadow-lg: 0 10px 15px rgba(0,0,0,0.1), 0 4px 6px rgba(0,0,0,0.05);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--gray-50);
  color: var(--gray-800);
  line-height: 1.6;
  min-height: 100vh;
}

/* ===== 导航栏 ===== */
.navbar {
  background: white;
  border-bottom: 1px solid var(--gray-200);
  padding: 0 24px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow);
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  cursor: pointer;
}

.nav-logo {
  background: var(--primary);
  color: white;
  font-weight: 800;
  font-size: 14px;
  padding: 4px 8px;
  border-radius: 6px;
  letter-spacing: -0.5px;
}

.nav-title {
  font-weight: 600;
  font-size: 16px;
  color: var(--gray-800);
}

.nav-links {
  display: flex;
  gap: 4px;
}

.nav-link {
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  color: var(--gray-600);
  font-size: 14px;
  font-weight: 500;
  transition: all 0.15s;
  text-decoration: none;
}

.nav-link:hover {
  background: var(--gray-100);
  color: var(--gray-800);
}

.nav-link.active {
  background: var(--primary-light);
  color: var(--primary);
}

/* ===== 主内容区 ===== */
#main-content {
  max-width: 900px;
  margin: 0 auto;
  padding: 32px 24px 80px;
}

/* ===== 通用组件 ===== */
.section-title {
  font-size: 18px;
  font-weight: 600;
  color: var(--gray-800);
  margin-bottom: 16px;
}

.section-hint {
  font-size: 13px;
  font-weight: 400;
  color: var(--gray-400);
}

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

/* Banner */
.banner {
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  margin-bottom: 20px;
  font-size: 14px;
}

.banner a {
  color: var(--primary);
  cursor: pointer;
  text-decoration: underline;
  font-weight: 500;
}

.banner-warning {
  background: var(--yellow-light);
  border: 1px solid #fcd34d;
  color: #92400e;
}

.banner-info {
  background: var(--primary-light);
  border: 1px solid #93c5fd;
  color: #1e40af;
}

/* 按钮 */
.btn {
  padding: 10px 20px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

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

.btn-primary {
  background: var(--primary);
  color: white;
}

.btn-primary:hover:not(:disabled) {
  background: var(--primary-dark);
}

.btn-secondary {
  background: var(--gray-100);
  color: var(--gray-700);
}

.btn-secondary:hover:not(:disabled) {
  background: var(--gray-200);
}

.btn-text {
  background: transparent;
  color: var(--gray-500);
}

.btn-text:hover:not(:disabled) {
  background: var(--gray-100);
  color: var(--gray-700);
}

.btn-danger {
  color: var(--red) !important;
}

.btn-danger:hover:not(:disabled) {
  background: var(--red-light) !important;
}

.btn-large {
  padding: 14px 32px;
  font-size: 16px;
  width: 100%;
  justify-content: center;
}

.btn-sm {
  padding: 4px 10px;
  font-size: 12px;
}

/* Spinner */
.spinner {
  display: inline-block;
  width: 14px;
  height: 14px;
  border: 2px solid currentColor;
  border-top-color: transparent;
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* 徽章 */
.badge {
  display: inline-block;
  padding: 2px 10px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 500;
}

.badge-blue { background: var(--primary-light); color: var(--primary); }
.badge-green { background: var(--green-light); color: var(--green); }
.badge-purple { background: var(--purple-light); color: var(--purple); }
.badge-gray { background: var(--gray-100); color: var(--gray-600); }
.badge-outline { background: transparent; border: 1px solid var(--gray-300); color: var(--gray-600); }

/* 输入控件 */
.select, .input {
  padding: 8px 12px;
  border: 1px solid var(--gray-300);
  border-radius: var(--radius-sm);
  font-size: 14px;
  background: white;
  color: var(--gray-800);
  outline: none;
  transition: border-color 0.15s;
}

.select:focus, .input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.select-sm {
  padding: 4px 8px;
  font-size: 12px;
}

/* ===== 首页 ===== */
.mode-tabs {
  display: flex;
  gap: 12px;
}

.mode-tab {
  flex: 1;
  padding: 20px;
  border: 2px solid var(--gray-200);
  border-radius: var(--radius);
  background: white;
  cursor: pointer;
  transition: all 0.15s;
  text-align: center;
}

.mode-tab:hover {
  border-color: var(--gray-300);
}

.mode-tab.active {
  border-color: var(--primary);
  background: var(--primary-light);
}

.mode-icon {
  font-size: 28px;
  display: block;
  margin-bottom: 8px;
}

.mode-name {
  font-weight: 600;
  font-size: 15px;
  display: block;
}

.mode-desc {
  font-size: 12px;
  color: var(--gray-500);
  display: block;
  margin-top: 4px;
}

/* 模块切换器 */
.module-tabs {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.module-tab {
  flex: 1;
  min-width: 140px;
  padding: 14px 16px;
  border: 2px solid var(--gray-200);
  border-radius: var(--radius);
  background: white;
  cursor: pointer;
  transition: all 0.15s;
  text-align: center;
}

.module-tab:hover {
  border-color: var(--gray-300);
  transform: translateY(-1px);
}

.module-tab.active {
  border-color: var(--primary);
  background: var(--primary-light);
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.12);
}

.module-icon {
  font-size: 22px;
  display: block;
  margin-bottom: 6px;
}

.module-name {
  font-weight: 600;
  font-size: 14px;
  display: block;
}

.module-desc {
  font-size: 11px;
  color: var(--gray-500);
  display: block;
  margin-top: 3px;
}

/* 学习中心的紧凑模块筛选 */
.module-tabs-sm .module-tab {
  flex: none;
  min-width: 0;
  padding: 8px 14px;
  border-width: 1.5px;
}

.module-tabs-sm .module-icon {
  font-size: 15px;
  display: inline;
  margin-bottom: 0;
  margin-right: 4px;
}

.module-tabs-sm .module-name {
  display: inline;
  font-size: 13px;
}

/* 模块徽章（答题页） */
.badge-module {
  background: var(--primary-light);
  color: var(--primary);
  border: 1px solid var(--primary);
}

/* 图表空态 */
.chart-empty {
  padding: 40px 20px;
  text-align: center;
  color: var(--gray-500);
  font-size: 13px;
}

/* 学习中心模块筛选区块 */
.stats-module-filter {
  margin-bottom: 16px;
}

/* 知识点卡片 */
.kp-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 10px;
}

.kp-card {
  display: flex;
  flex-direction: column;
  padding: 12px;
  border: 2px solid var(--gray-200);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.15s;
  position: relative;
}

.kp-card:hover {
  border-color: var(--gray-300);
  background: var(--gray-50);
}

.kp-card input[type="checkbox"] {
  position: absolute;
  top: 10px;
  right: 10px;
  width: 16px;
  height: 16px;
  cursor: pointer;
}

.kp-card:has(input:checked) {
  border-color: var(--primary);
  background: var(--primary-light);
}

.kp-card-all {
  background: var(--gray-50);
}

.kp-icon {
  font-size: 20px;
  margin-bottom: 4px;
}

.kp-name {
  font-weight: 600;
  font-size: 13px;
  color: var(--gray-800);
}

.kp-desc {
  font-size: 11px;
  color: var(--gray-500);
  margin-top: 2px;
  line-height: 1.4;
}

/* 选项行 */
.options-row {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
}

.option-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.option-label {
  font-size: 13px;
  font-weight: 500;
  color: var(--gray-600);
}

.checkbox-group {
  display: flex;
  gap: 8px;
}

.chip {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 6px 12px;
  border: 1px solid var(--gray-300);
  border-radius: 20px;
  font-size: 13px;
  cursor: pointer;
  transition: all 0.15s;
}

.chip input {
  margin: 0;
  cursor: pointer;
}

.chip:has(input:checked) {
  border-color: var(--primary);
  background: var(--primary-light);
  color: var(--primary);
}

/* ===== 答题页 ===== */
.quiz-header {
  margin-bottom: 20px;
}

.quiz-progress-bar {
  height: 6px;
  background: var(--gray-200);
  border-radius: 3px;
  overflow: hidden;
}

.quiz-progress-fill {
  height: 100%;
  background: var(--primary);
  border-radius: 3px;
  transition: width 0.3s;
}

.quiz-progress-text {
  font-size: 13px;
  color: var(--gray-500);
  margin-top: 6px;
}

.quiz-card {
  background: white;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 28px;
  box-shadow: var(--shadow);
}

.quiz-meta {
  display: flex;
  gap: 6px;
  margin-bottom: 16px;
  flex-wrap: wrap;
}

.quiz-question {
  font-size: 16px;
  font-weight: 500;
  color: var(--gray-900);
  margin-bottom: 20px;
  line-height: 1.7;
  white-space: pre-wrap;
}

.quiz-answer-area {
  margin-bottom: 20px;
}

/* 选择题选项 */
.option-item {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 12px 16px;
  border: 2px solid var(--gray-200);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.15s;
  margin-bottom: 8px;
}

.option-item:hover {
  border-color: var(--gray-300);
  background: var(--gray-50);
}

.option-item.selected {
  border-color: var(--primary);
  background: var(--primary-light);
}

.option-letter {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--gray-100);
  color: var(--gray-600);
  font-weight: 600;
  font-size: 13px;
  flex-shrink: 0;
}

.option-item.selected .option-letter {
  background: var(--primary);
  color: white;
}

.option-text {
  font-size: 14px;
  color: var(--gray-700);
  padding-top: 3px;
}

/* 填空题 */
.fill-input {
  width: 100%;
  padding: 12px 16px;
  border: 2px solid var(--gray-300);
  border-radius: var(--radius-sm);
  font-size: 15px;
  outline: none;
  transition: border-color 0.15s;
}

.fill-input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* 简答题 */
.short-input {
  width: 100%;
  padding: 12px 16px;
  border: 2px solid var(--gray-300);
  border-radius: var(--radius-sm);
  font-size: 14px;
  outline: none;
  resize: vertical;
  font-family: inherit;
  transition: border-color 0.15s;
}

.short-input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.quiz-actions {
  display: flex;
  gap: 12px;
  align-items: center;
}

/* 反馈区 */
.feedback-card {
  background: white;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 20px;
  margin-top: 16px;
  box-shadow: var(--shadow);
}

.feedback-correct {
  border-left: 4px solid var(--green);
}

.feedback-wrong {
  border-left: 4px solid var(--red);
}

.feedback-result {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 16px;
  white-space: pre-wrap;
}

.feedback-section {
  margin-bottom: 14px;
}

.feedback-label {
  font-size: 12px;
  font-weight: 600;
  color: var(--gray-500);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 4px;
}

.feedback-content {
  font-size: 14px;
  color: var(--gray-700);
  padding: 8px 12px;
  background: var(--gray-50);
  border-radius: var(--radius-sm);
}

.content-correct {
  color: var(--green);
}

.content-wrong {
  color: var(--red);
}

.feedback-explanation {
  font-size: 14px;
  color: var(--gray-700);
  line-height: 1.7;
  padding: 12px;
  background: var(--gray-50);
  border-radius: var(--radius-sm);
  white-space: pre-wrap;
}

/* ===== 结果页 ===== */
.page-result {
  text-align: center;
}

.result-hero {
  background: white;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 40px;
  margin-bottom: 24px;
  box-shadow: var(--shadow);
}

.result-emoji {
  font-size: 48px;
  margin-bottom: 12px;
}

.result-score {
  font-size: 56px;
  font-weight: 800;
  line-height: 1;
}

.result-score-unit {
  font-size: 20px;
  font-weight: 500;
}

.result-grade {
  font-size: 20px;
  font-weight: 600;
  margin: 8px 0;
}

.result-detail {
  font-size: 14px;
  color: var(--gray-500);
}

.result-section {
  background: white;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 24px;
  text-align: left;
  box-shadow: var(--shadow);
}

.result-wrong-item {
  padding: 12px;
  border-bottom: 1px solid var(--gray-100);
}

.result-wrong-item:last-child {
  border-bottom: none;
}

.result-wrong-q {
  font-size: 14px;
  font-weight: 500;
  color: var(--gray-800);
  margin-bottom: 6px;
}

.result-wrong-a {
  font-size: 13px;
  margin: 2px 0;
}

.result-actions {
  display: flex;
  gap: 12px;
  justify-content: center;
}

/* ===== 学习中心 ===== */
.page-stats {
  max-width: 900px;
}

.stats-overview {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  margin-bottom: 24px;
}

.stat-card {
  background: white;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 20px;
  text-align: center;
  box-shadow: var(--shadow);
}

.stat-value {
  font-size: 28px;
  font-weight: 800;
  color: var(--gray-800);
}

.stat-label {
  font-size: 13px;
  color: var(--gray-500);
  margin-top: 4px;
}

.text-green { color: var(--green) !important; }
.text-red { color: var(--red) !important; }

.stats-charts {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-bottom: 24px;
}

.chart-card {
  background: white;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
}

.chart-title {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 12px;
  color: var(--gray-700);
}

/* 错题本 */
.wrong-book {
  background: white;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
}

.wrong-book-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
  flex-wrap: wrap;
  gap: 8px;
}

.wrong-book-actions {
  display: flex;
  gap: 8px;
  align-items: center;
}

.wrong-item {
  padding: 14px;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-sm);
  margin-bottom: 10px;
}

.wrong-item-header {
  display: flex;
  gap: 6px;
  align-items: center;
  margin-bottom: 8px;
}

.wrong-item-q {
  font-size: 14px;
  font-weight: 500;
  color: var(--gray-800);
  margin-bottom: 6px;
}

.wrong-item-a {
  font-size: 13px;
  margin: 2px 0;
}

.wrong-item-explain {
  font-size: 13px;
  color: var(--gray-600);
  background: var(--gray-50);
  padding: 8px;
  border-radius: var(--radius-sm);
  margin-top: 6px;
  line-height: 1.6;
}

.empty-state {
  text-align: center;
  padding: 40px;
  color: var(--gray-400);
  font-size: 15px;
}

/* ===== 设置页 ===== */
.page-settings {
  max-width: 700px;
}

.settings-section {
  background: white;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 20px;
  box-shadow: var(--shadow);
}

.form-group {
  margin-bottom: 16px;
}

.form-label {
  display: block;
  font-size: 13px;
  font-weight: 500;
  color: var(--gray-600);
  margin-bottom: 6px;
}

.input {
  width: 100%;
}

.checkbox-label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  color: var(--gray-700);
  cursor: pointer;
}

.checkbox-label input {
  width: 16px;
  height: 16px;
  cursor: pointer;
}

.form-actions {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

/* ===== Toast ===== */
#toast-container {
  position: fixed;
  top: 70px;
  right: 24px;
  z-index: 9999;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.toast {
  padding: 12px 20px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  color: white;
  box-shadow: var(--shadow-lg);
  opacity: 0;
  transform: translateX(20px);
  transition: all 0.3s;
  max-width: 350px;
}

.toast.show {
  opacity: 1;
  transform: translateX(0);
}

.toast-success { background: var(--green); }
.toast-error { background: var(--red); }
.toast-info { background: var(--gray-600); }

/* ===== 响应式 ===== */
@media (max-width: 768px) {
  .nav-title { display: none; }
  .nav-links { gap: 2px; }
  .nav-link { padding: 6px 10px; font-size: 13px; }

  #main-content { padding: 20px 16px 60px; }

  .mode-tabs { flex-direction: column; }
  .module-tabs { flex-direction: column; }
  .module-tab { min-width: 0; }
  .module-tabs-sm { flex-direction: row; overflow-x: auto; flex-wrap: nowrap; }

  .kp-grid {
    grid-template-columns: 1fr;
  }

  .options-row { flex-direction: column; gap: 12px; }

  .stats-overview {
    grid-template-columns: repeat(2, 1fr);
  }

  .stats-charts {
    grid-template-columns: 1fr;
  }

  .quiz-card { padding: 16px; }
  .result-hero { padding: 24px; }
}