/* ==========================================================================
   《光电子器件》全考点三刷通关与草稿纸辅助计算系统 - 浅色主题样式表 (Light Theme)
   ========================================================================== */

:root {
  --bg-page: #f8fafc;
  --bg-surface: #ffffff;
  --bg-subtle: #f1f5f9;
  --bg-accent-soft: #eff6ff;
  --bg-paper: #fffef8;
  --border-light: #e2e8f0;
  --border-medium: #cbd5e1;
  --border-paper: #e5dec9;

  --text-primary: #0f172a;
  --text-secondary: #334155;
  --text-muted: #64748b;

  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --primary-light: #dbeafe;

  --pass1-color: #3b82f6;
  --pass1-bg: #eff6ff;
  --pass2-color: #8b5cf6;
  --pass2-bg: #f5f3ff;
  --pass3-color: #10b981;
  --pass3-bg: #ecfdf5;

  --success: #10b981;
  --success-bg: #ecfdf5;
  --success-border: #a7f3d0;

  --warning: #f59e0b;
  --warning-bg: #fffbeb;
  --warning-border: #fde68a;

  --danger: #ef4444;
  --danger-bg: #fef2f2;
  --danger-border: #fecaca;

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.06);
  --shadow-md: 0 4px 12px rgba(15, 23, 42, 0.07);
  --shadow-lg: 0 10px 25px rgba(15, 23, 42, 0.1);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background-color: var(--bg-page);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
}

/* 顶部导航与全局三刷进度栏 */
.top-header {
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border-light);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow-sm);
}

.header-inner {
  max-width: 1440px;
  margin: 0 auto;
  padding: 12px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
}

.brand-area {
  display: flex;
  align-items: center;
  gap: 12px;
}

.brand-logo {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  background: linear-gradient(135deg, #2563eb, #4f46e5);
  color: #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 18px;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.25);
}

.brand-title h1 {
  font-size: 18px;
  font-weight: 700;
  color: var(--text-primary);
}

.brand-title p {
  font-size: 12px;
  color: var(--text-muted);
}

/* 顶部模式切换导航标签 */
.nav-tabs {
  display: flex;
  align-items: center;
  gap: 6px;
  background: var(--bg-subtle);
  padding: 4px;
  border-radius: var(--radius-md);
}

.nav-tab {
  border: none;
  background: transparent;
  color: var(--text-secondary);
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  font-size: 13.5px;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: all 0.18s ease;
}

.nav-tab:hover {
  color: var(--primary);
  background: rgba(255, 255, 255, 0.6);
}

.nav-tab.active {
  background: var(--bg-surface);
  color: var(--primary);
  box-shadow: var(--shadow-sm);
}

.badge-pill {
  font-size: 11px;
  padding: 1px 7px;
  border-radius: 999px;
  font-weight: 700;
}

.badge-danger {
  background: var(--danger-bg);
  color: var(--danger);
  border: 1px solid var(--danger-border);
}

.badge-primary {
  background: var(--primary-light);
  color: var(--primary);
}

.badge-success {
  background: var(--success-bg);
  color: var(--success);
}

/* 三刷全局统计条 */
.global-stats {
  display: flex;
  align-items: center;
  gap: 14px;
}

.stat-chip {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 12.5px;
  padding: 5px 10px;
  border-radius: var(--radius-sm);
  background: var(--bg-subtle);
  color: var(--text-secondary);
  border: 1px solid var(--border-light);
}

.stat-chip strong {
  font-weight: 700;
}

.stat-chip.pass1 strong { color: var(--pass1-color); }
.stat-chip.pass2 strong { color: var(--pass2-color); }
.stat-chip.pass3 strong { color: var(--pass3-color); }

/* 主体布局容器 */
.app-container {
  max-width: 1440px;
  margin: 0 auto;
  padding: 20px 24px 48px;
  display: grid;
  grid-template-columns: 290px 1fr 330px;
  gap: 20px;
  align-items: start;
}

@media (max-width: 1200px) {
  .app-container {
    grid-template-columns: 260px 1fr;
  }
  .right-sidebar {
    grid-column: 1 / -1;
  }
}

@media (max-width: 860px) {
  .app-container {
    grid-template-columns: 1fr;
  }
}

/* 左侧栏：章节与三刷筛选器 */
.left-sidebar, .right-sidebar {
  background: var(--bg-surface);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 16px;
  box-shadow: var(--shadow-sm);
}

.sidebar-section {
  margin-bottom: 18px;
}

.sidebar-section:last-child {
  margin-bottom: 0;
}

.sidebar-title {
  font-size: 13px;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

/* 三刷进度总览卡片 */
.mastery-overview-card {
  background: linear-gradient(180deg, #f8fafc 0%, #eff6ff 100%);
  border: 1px solid #bfdbfe;
  border-radius: var(--radius-md);
  padding: 12px;
  margin-bottom: 16px;
}

.progress-row {
  margin-bottom: 10px;
}

.progress-row:last-child {
  margin-bottom: 0;
}

.progress-label {
  display: flex;
  justify-content: space-between;
  font-size: 12px;
  font-weight: 600;
  margin-bottom: 4px;
}

.progress-bar-track {
  height: 7px;
  background: #e2e8f0;
  border-radius: 999px;
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  border-radius: 999px;
  transition: width 0.35s ease;
}

.fill-pass1 { background: var(--pass1-color); }
.fill-pass2 { background: var(--pass2-color); }
.fill-pass3 { background: var(--pass3-color); }

/* 筛选按钮组 */
.filter-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.filter-chip {
  font-size: 12px;
  padding: 5px 10px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-light);
  background: var(--bg-surface);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.15s;
}

.filter-chip:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.filter-chip.active {
  background: var(--primary);
  color: #ffffff;
  border-color: var(--primary);
  font-weight: 600;
}

/* 章节树列表 */
.chapter-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.chapter-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 9px 11px;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  background: var(--bg-page);
  cursor: pointer;
  transition: all 0.15s;
  font-size: 13px;
}

.chapter-item:hover {
  background: var(--bg-accent-soft);
  border-color: #bfdbfe;
}

.chapter-item.active {
  background: var(--bg-accent-soft);
  border-color: var(--primary);
  color: var(--primary);
  font-weight: 600;
}

.chapter-meta {
  font-size: 11.5px;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  gap: 4px;
}

/* 中央主刷题区域 */
.main-stage {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

/* 考点题目导航网格条 */
.question-strip-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 14px 18px;
  box-shadow: var(--shadow-sm);
}

.strip-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 10px;
  flex-wrap: wrap;
  gap: 8px;
}

.strip-header-left {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
}

.strip-legend {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 11.5px;
  color: var(--text-muted);
}

.legend-dot {
  display: inline-block;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  margin-right: 4px;
}

.question-dots-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  max-height: 115px;
  overflow-y: auto;
  padding: 2px;
}

.q-dot {
  min-width: 36px;
  height: 30px;
  padding: 0 6px;
  border-radius: 6px;
  border: 1px solid var(--border-light);
  background: var(--bg-page);
  font-size: 11.5px;
  font-weight: 600;
  color: var(--text-secondary);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  position: relative;
  transition: all 0.15s;
}

.q-dot:hover {
  border-color: var(--primary);
  transform: translateY(-1px);
}

.q-dot.current {
  outline: 2px solid var(--primary);
  outline-offset: 1px;
  font-weight: 700;
}

.q-dot.pass-0 { background: #ffffff; }
.q-dot.pass-1 { background: var(--pass1-bg); border-color: #93c5fd; color: #1d4ed8; }
.q-dot.pass-2 { background: var(--pass2-bg); border-color: #c4b5fd; color: #6d28d9; }
.q-dot.pass-3 { background: var(--pass3-bg); border-color: #6ee7b7; color: #047857; }

.q-dot.has-wrong::after {
  content: "";
  position: absolute;
  top: -3px;
  right: -3px;
  width: 8px;
  height: 8px;
  background: var(--danger);
  border-radius: 50%;
  border: 1.5px solid #fff;
}

.q-dot-stars {
  font-size: 8px;
  line-height: 1;
  letter-spacing: -1px;
}

/* 题目主卡片 */
.question-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--shadow-md);
}

.q-card-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--border-light);
  margin-bottom: 18px;
  flex-wrap: wrap;
}

.q-tags {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 8px;
}

.q-tag {
  font-size: 12px;
  font-weight: 600;
  padding: 3px 9px;
  border-radius: var(--radius-sm);
}

.tag-chapter {
  background: var(--bg-subtle);
  color: var(--text-secondary);
}

.tag-type-term { background: #e0f2fe; color: #0369a1; }
.tag-type-short { background: #fef3c7; color: #b45309; }
.tag-type-calc { background: #fce7f3; color: #be185d; }

.tag-pdf {
  background: #f1f5f9;
  color: #475569;
  border: 1px dashed #94a3b8;
  cursor: pointer;
}

.tag-pdf:hover {
  background: #e2e8f0;
  color: var(--primary);
}

.q-title {
  font-size: 20px;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.4;
}

/* 三刷状态徽章与切换器 */
.pass-controller {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 8px;
}

.pass-stars-badge {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  border-radius: 999px;
  font-size: 13px;
  font-weight: 700;
  border: 1px solid var(--border-light);
  background: var(--bg-page);
}

.star-icon {
  font-size: 16px;
  color: #cbd5e1;
  transition: transform 0.2s, color 0.2s;
}

.star-icon.filled-1 { color: var(--pass1-color); }
.star-icon.filled-2 { color: var(--pass2-color); }
.star-icon.filled-3 { color: var(--pass3-color); }

/* 刷次阶段切换按钮（一刷 / 二刷 / 三刷） */
.stage-switcher {
  display: flex;
  gap: 6px;
  background: var(--bg-subtle);
  padding: 4px;
  border-radius: var(--radius-md);
  margin-bottom: 18px;
}

.stage-btn {
  flex: 1;
  padding: 9px 12px;
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  background: transparent;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  transition: all 0.15s;
}

.stage-btn:hover {
  background: rgba(255, 255, 255, 0.7);
}

.stage-btn.active.stage-1 {
  background: var(--bg-surface);
  color: var(--pass1-color);
  border-color: #bfdbfe;
  box-shadow: var(--shadow-sm);
}

.stage-btn.active.stage-2 {
  background: var(--bg-surface);
  color: var(--pass2-color);
  border-color: #ddd6fe;
  box-shadow: var(--shadow-sm);
}

.stage-btn.active.stage-3 {
  background: var(--bg-surface);
  color: var(--pass3-color);
  border-color: #a7f3d0;
  box-shadow: var(--shadow-sm);
}

/* 题干与图表展示框 */
.q-prompt-box {
  font-size: 15.5px;
  color: var(--text-primary);
  margin-bottom: 18px;
  line-height: 1.7;
}

.diagram-container {
  background: #ffffff;
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 14px;
  margin: 14px 0;
  text-align: center;
}

.diagram-caption {
  font-size: 12px;
  color: var(--text-muted);
  margin-top: 6px;
}

/* 一刷：选择题选项样式 */
.mcq-options {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 18px;
}

.mcq-option {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 13px 16px;
  border: 1.5px solid var(--border-light);
  border-radius: var(--radius-md);
  background: var(--bg-surface);
  cursor: pointer;
  transition: all 0.15s;
  font-size: 14.5px;
  text-align: left;
}

.mcq-option:hover:not(.disabled) {
  border-color: var(--primary);
  background: var(--bg-accent-soft);
}

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

.mcq-option.correct {
  border-color: var(--success);
  background: var(--success-bg);
  color: #065f46;
}

.mcq-option.wrong {
  border-color: var(--danger);
  background: var(--danger-bg);
  color: #991b1b;
}

.option-letter {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--bg-subtle);
  color: var(--text-secondary);
  font-weight: 700;
  font-size: 13px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

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

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

/* 二刷：挖空填空与关键词自检 */
.cloze-box {
  background: var(--bg-page);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 18px;
  margin-bottom: 16px;
  font-size: 15px;
  line-height: 2;
}

.cloze-input {
  border: none;
  border-bottom: 2px solid var(--primary);
  background: #ffffff;
  padding: 2px 8px;
  margin: 0 4px;
  font-size: 14.5px;
  font-weight: 600;
  color: var(--primary);
  border-radius: 4px 4px 0 0;
  min-width: 110px;
  text-align: center;
  transition: all 0.15s;
}

.cloze-input:focus {
  outline: none;
  background: #eff6ff;
  box-shadow: 0 2px 6px rgba(37, 99, 235, 0.15);
}

.cloze-input.correct {
  border-bottom-color: var(--success);
  background: var(--success-bg);
  color: #047857;
}

.cloze-input.wrong {
  border-bottom-color: var(--danger);
  background: var(--danger-bg);
  color: #b91c1c;
}

/* 三刷：闭卷默写与采分点核对清单 */
.recall-area {
  margin-bottom: 16px;
}

.recall-textarea {
  width: 100%;
  min-height: 95px;
  padding: 12px 14px;
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-md);
  font-size: 14px;
  font-family: inherit;
  resize: vertical;
  background: var(--bg-paper);
  margin-bottom: 12px;
}

.recall-textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.12);
}

.rubric-checklist {
  background: #f8fafc;
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 14px 16px;
  margin-top: 12px;
}

.rubric-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 7px 0;
  border-bottom: 1px dashed var(--border-light);
  font-size: 14px;
  cursor: pointer;
}

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

.rubric-item input[type="checkbox"] {
  margin-top: 4px;
  width: 16px;
  height: 16px;
  accent-color: var(--success);
  cursor: pointer;
}

/* ==========================================================================
   现实草稿纸辅助计算工作台 (Paper Scratchpad Calculation Workbench)
   ========================================================================== */
.scratchpad-workbench {
  background: var(--bg-paper);
  border: 2px solid var(--border-paper);
  border-radius: var(--radius-lg);
  padding: 20px;
  margin-bottom: 18px;
  position: relative;
  background-image: radial-gradient(#d8d0b8 0.75px, transparent 0.75px);
  background-size: 18px 18px;
}

.scratchpad-banner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: #fef3c7;
  border: 1px solid #fde68a;
  color: #92400e;
  padding: 10px 14px;
  border-radius: var(--radius-md);
  margin-bottom: 16px;
  flex-wrap: wrap;
  gap: 10px;
}

.scratchpad-code {
  font-family: "Consolas", "SFMono-Regular", monospace;
  font-weight: 800;
  font-size: 13.5px;
  background: #ffffff;
  padding: 3px 9px;
  border-radius: 5px;
  border: 1px solid #f59e0b;
  color: #b45309;
}

.given-params-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(185px, 1fr));
  gap: 10px;
  margin-bottom: 16px;
}

.param-box {
  background: rgba(255, 255, 255, 0.92);
  border: 1px solid var(--border-paper);
  border-radius: var(--radius-sm);
  padding: 9px 12px;
  font-size: 13px;
}

.param-box .param-name {
  color: var(--text-muted);
  font-size: 11.5px;
  display: block;
}

.param-box .param-val {
  font-weight: 700;
  color: var(--text-primary);
  font-size: 14.5px;
  font-family: "Consolas", monospace;
}

/* 草稿纸分步验算卡片 */
.calc-steps-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.calc-step-card {
  background: rgba(255, 255, 255, 0.96);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-md);
  padding: 14px 16px;
  transition: all 0.2s;
}

.calc-step-card.step-correct {
  border-color: var(--success);
  background: #f0fdf4;
}

.calc-step-card.step-wrong {
  border-color: var(--danger);
  background: #fef2f2;
}

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

.step-title {
  font-weight: 700;
  font-size: 14px;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 8px;
}

.step-badge {
  background: var(--primary-light);
  color: var(--primary);
  font-size: 11.5px;
  padding: 2px 8px;
  border-radius: 4px;
  font-weight: 700;
}

.step-hint-btn {
  font-size: 12px;
  color: var(--primary);
  background: transparent;
  border: 1px dashed var(--primary);
  padding: 2px 8px;
  border-radius: 4px;
  cursor: pointer;
}

.step-formula-hint {
  font-size: 13px;
  color: #475569;
  background: #f8fafc;
  border-left: 3px solid var(--primary);
  padding: 6px 10px;
  margin: 6px 0 10px;
  border-radius: 0 4px 4px 0;
}

.step-input-row {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.step-num-input {
  padding: 8px 12px;
  border: 1.5px solid var(--border-medium);
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-weight: 600;
  font-family: "Consolas", monospace;
  width: 160px;
  background: #ffffff;
}

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

.step-unit {
  font-size: 13.5px;
  font-weight: 600;
  color: var(--text-secondary);
}

.step-feedback {
  font-size: 12.5px;
  font-weight: 600;
  margin-top: 6px;
}

/* 标准答案与解析框 */
.explanation-panel {
  background: #f8fafc;
  border: 1px solid #cbd5e1;
  border-left: 4px solid var(--primary);
  border-radius: var(--radius-md);
  padding: 16px 18px;
  margin-top: 18px;
}

.explanation-title {
  font-size: 14px;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.explanation-body {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.75;
}

/* 通用按钮 */
.btn-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-top: 18px;
  flex-wrap: wrap;
}

.btn {
  padding: 9px 16px;
  border-radius: var(--radius-sm);
  font-size: 13.5px;
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: all 0.15s;
}

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

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

.btn-success {
  background: var(--success);
  color: #ffffff;
}

.btn-success:hover {
  background: #059669;
}

.btn-danger {
  background: var(--danger-bg);
  color: var(--danger);
  border-color: var(--danger-border);
}

.btn-danger:hover {
  background: #fee2e2;
}

.btn-outline {
  background: var(--bg-surface);
  color: var(--text-secondary);
  border-color: var(--border-medium);
}

.btn-outline:hover {
  border-color: var(--primary);
  color: var(--primary);
  background: var(--bg-accent-soft);
}

.btn-sm {
  padding: 5px 10px;
  font-size: 12px;
}

/* 右侧栏：光电科学计算器 & 常数表 & 笔记快速预览 */
.calc-widget {
  background: var(--bg-page);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 12px;
  margin-bottom: 16px;
}

.calc-screen {
  width: 100%;
  padding: 8px 10px;
  font-family: "Consolas", monospace;
  font-size: 15px;
  font-weight: 700;
  text-align: right;
  background: #ffffff;
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-sm);
  margin-bottom: 6px;
  color: var(--text-primary);
}

.calc-result-preview {
  font-size: 12px;
  color: var(--primary);
  text-align: right;
  min-height: 18px;
  margin-bottom: 8px;
  font-family: "Consolas", monospace;
  font-weight: 600;
}

.calc-keys-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 5px;
}

.calc-key {
  padding: 7px 4px;
  font-size: 12px;
  font-weight: 600;
  background: #ffffff;
  border: 1px solid var(--border-light);
  border-radius: 5px;
  cursor: pointer;
  color: var(--text-secondary);
  transition: all 0.12s;
}

.calc-key:hover {
  background: var(--bg-accent-soft);
  border-color: var(--primary);
  color: var(--primary);
}

.calc-key.key-fn {
  background: #eff6ff;
  color: #1d4ed8;
}

.calc-key.key-eq {
  background: var(--primary);
  color: #ffffff;
  border-color: var(--primary);
}

/* 快捷换算工具条 */
.quick-converter {
  background: #ffffff;
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  padding: 10px;
  margin-top: 8px;
  font-size: 12px;
}

.converter-row {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-top: 6px;
}

.converter-row input {
  width: 100%;
  padding: 4px 7px;
  border: 1px solid var(--border-medium);
  border-radius: 4px;
  font-size: 12px;
  font-family: "Consolas", monospace;
}

/* 常数表 */
.constants-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-size: 12px;
}

.const-item {
  display: flex;
  justify-content: space-between;
  padding: 6px 8px;
  background: var(--bg-page);
  border-radius: 5px;
  border: 1px solid var(--border-light);
}

.const-item code {
  font-family: "Consolas", monospace;
  font-weight: 700;
  color: var(--primary);
}

/* 错题本列表视图 */
.wrong-book-container {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.wrong-item-card {
  background: var(--bg-surface);
  border: 1px solid var(--danger-border);
  border-left: 5px solid var(--danger);
  border-radius: var(--radius-md);
  padding: 16px 20px;
  box-shadow: var(--shadow-sm);
}

.wrong-item-card.resolved {
  border-color: var(--success-border);
  border-left-color: var(--success);
  opacity: 0.88;
}

.wrong-meta-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 8px;
  flex-wrap: wrap;
}

.wrong-note-input {
  width: 100%;
  padding: 8px 10px;
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-sm);
  font-size: 13px;
  margin-top: 8px;
  background: #fffbeb;
}

/* 原版手写笔记弹窗 / 预览框 */
.modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 42, 0.55);
  z-index: 999;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.modal-backdrop.open {
  display: flex;
}

.modal-window {
  background: var(--bg-surface);
  border-radius: var(--radius-lg);
  max-width: 980px;
  width: 100%;
  max-height: 90vh;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-lg);
  overflow: hidden;
}

.modal-header {
  padding: 14px 20px;
  border-bottom: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.modal-body {
  padding: 18px;
  overflow-y: auto;
  text-align: center;
  background: var(--bg-subtle);
}

.modal-body img {
  max-width: 100%;
  height: auto;
  border-radius: 8px;
  box-shadow: var(--shadow-md);
  border: 1px solid var(--border-light);
}

/* 知识点背诵全景表视图 */
.knowledge-table-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 20px;
  box-shadow: var(--shadow-sm);
}

.kp-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 14px;
  margin-top: 14px;
}

.kp-summary-card {
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 14px;
  background: var(--bg-page);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 10px;
}

@media print {
  .top-header, .left-sidebar, .right-sidebar, .question-strip-card, .stage-switcher, .btn-row {
    display: none !important;
  }
  .app-container {
    display: block;
    padding: 0;
  }
}

/* ==========================================================================
   直观数学分式与公式排版样式（纯本地零依赖渲染上下分式、上下标与公式块）
   ========================================================================== */
.formula-card {
  display: block;
  background: #ffffff;
  border: 1px solid #dbeafe;
  border-left: 4px solid #2563eb;
  border-radius: 8px;
  padding: 10px 16px;
  margin: 10px 0;
  font-family: "Cambria Math", "Times New Roman", "STIXGeneral", serif;
  font-size: 16px;
  color: #0f172a;
  line-height: 1.8;
  box-shadow: 0 1px 2px rgba(15, 23, 42, 0.04);
}

.math-inline {
  font-family: "Cambria Math", "Times New Roman", serif;
  font-size: 1.05em;
  color: #0f172a;
  padding: 0 2px;
}

.frac {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  vertical-align: middle;
  margin: 0 4px;
  line-height: 1.25;
  font-family: "Cambria Math", "Times New Roman", serif;
}

.frac-num {
  border-bottom: 1.5px solid #1e293b;
  padding: 0 5px 2px;
  text-align: center;
  width: 100%;
}

.frac-den {
  padding: 2px 5px 0;
  text-align: center;
  width: 100%;
}