:root {
  --bg: #0f1419;
  --surface: #1a2332;
  --surface-active: #1f2b3e;
  --border: #2d3a4f;
  --border-active: #3b82f6;
  --text: #e7ecf3;
  --muted: #8b9cb3;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --user-bg: #1e3a5f;
  --assistant-bg: #243044;
  --error: #f87171;
  --success: #4ade80;
  --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.3);
  --shadow-active: 0 4px 20px rgba(59, 130, 246, 0.12), 0 1px 3px rgba(0, 0, 0, 0.3);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC",
    "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.5;
}

.header {
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border);
}

.header-row {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
}

.voice-status {
  margin-top: 0.5rem;
  font-size: 0.85rem;
  color: var(--muted);
}

.header h1 {
  font-size: 1.35rem;
  font-weight: 600;
}

.subtitle {
  color: var(--muted);
  font-size: 0.9rem;
  margin-top: 0.25rem;
}

.status-banner {
  margin-top: 0.75rem;
  padding: 0.6rem 0.9rem;
  border-radius: 8px;
  font-size: 0.85rem;
}

.status-banner.error {
  background: rgba(248, 113, 113, 0.15);
  color: var(--error);
  border: 1px solid rgba(248, 113, 113, 0.35);
}

.status-banner.ok {
  background: rgba(74, 222, 128, 0.12);
  color: var(--success);
  border: 1px solid rgba(74, 222, 128, 0.3);
}

.hidden {
  display: none !important;
}

.layout {
  padding: 0.75rem 1.5rem 1rem;
  max-width: 1400px;
  margin: 0 auto;
  display: grid;
  /* 左栏 PDF 常驻，右栏为原有步骤内容 */
  grid-template-columns: minmax(280px, 38%) minmax(0, 1fr);
  gap: 1rem;
  align-items: start;
}

/* 未上传 PDF 时隐藏左栏，右栏恢复单列居中，保持原有观感 */
.layout.no-pdf {
  grid-template-columns: minmax(0, 1fr);
  max-width: 720px;
}

.layout.no-pdf .pdf-pane {
  display: none;
}

/* 左栏收起：只留一条窄边可再次展开 */
.layout.pdf-collapsed {
  grid-template-columns: 2.75rem minmax(0, 1fr);
}

.layout.pdf-collapsed .pdf-pane-body,
.layout.pdf-collapsed .pdf-pane-title,
.layout.pdf-collapsed .pdf-select {
  display: none;
}

.pdf-pane {
  position: sticky;
  top: 0.75rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 0.6rem;
  box-shadow: var(--shadow-card);
  max-height: calc(100vh - 8rem);
  min-height: 20rem;
  overflow: hidden;
}

.layout.pdf-collapsed .pdf-pane {
  min-height: 0;
  padding: 0.5rem 0.25rem;
}

.pdf-pane-head {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  min-width: 0;
}

.pdf-pane-title {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--muted);
  white-space: nowrap;
}

.pdf-select {
  flex: 1;
  min-width: 0;
  padding: 0.3rem 0.4rem;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text);
  font-family: inherit;
  font-size: 0.8rem;
}

.pdf-toggle {
  width: 1.9rem;
  height: 1.9rem;
  flex-shrink: 0;
  font-size: 1rem;
}

.pdf-pane-body {
  flex: 1;
  min-height: 0;
  border-radius: 8px;
  overflow: hidden;
  background: var(--bg);
}

.pdf-frame {
  width: 100%;
  height: 100%;
  min-height: 18rem;
  border: none;
  display: block;
}

.pdf-empty {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100%;
  padding: 1rem;
  text-align: center;
}

/* 窄屏：左右双栏改为上下堆叠，PDF 默认折叠避免挤压主流程 */
@media (max-width: 900px) {
  .layout,
  .layout.pdf-collapsed {
    grid-template-columns: minmax(0, 1fr);
  }

  .pdf-pane {
    position: static;
    max-height: 60vh;
    min-height: 0;
  }

  .layout.pdf-collapsed .pdf-pane {
    max-height: none;
  }
}

@media (max-width: 768px) {
  .layout {
    padding: 0.75rem 1rem;
  }
}

.stepper {
  display: flex;
  align-items: flex-start;
  gap: 0;
  margin-top: 0.75rem;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: thin;
  padding-bottom: 0.3rem;
}

.stepper::-webkit-scrollbar {
  height: 4px;
}

.stepper::-webkit-scrollbar-thumb {
  background: rgba(139, 156, 179, 0.3);
  border-radius: 999px;
}

.stepper-item {
  position: relative;
  flex: 1 1 0;
  min-width: 5rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.3rem;
  padding: 0.4rem 0.2rem;
  font-size: 0.72rem;
  border: none;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  font-family: inherit;
  transition: color 0.15s;
}

/* 连接线：除第一个外，每个 item 左侧画一条线连到前一个 */
.stepper-item:not(:first-child)::before {
  content: "";
  position: absolute;
  top: calc(0.4rem + 0.85rem);
  left: -50%;
  width: 100%;
  height: 2px;
  background: var(--border);
  z-index: 0;
  transition: background 0.2s;
}

.stepper-item.done:not(:first-child)::before,
.stepper-item.active:not(:first-child)::before {
  background: var(--accent);
}

.stepper-num {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 1.7rem;
  height: 1.7rem;
  border-radius: 50%;
  border: 2px solid var(--border);
  background: var(--bg);
  color: var(--muted);
  font-size: 0.8rem;
  font-weight: 600;
  transition: all 0.2s;
}

.stepper-label {
  text-align: center;
  line-height: 1.2;
}

.stepper-item:hover:not(:disabled) .stepper-num {
  border-color: var(--accent);
  color: var(--text);
}

.stepper-item:hover:not(:disabled) {
  color: var(--text);
}

.stepper-item.active .stepper-num {
  border-color: var(--accent);
  background: var(--accent);
  color: #fff;
  box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.18);
}

.stepper-item.active {
  color: #dce9ff;
  font-weight: 600;
}

.stepper-item.done .stepper-num {
  border-color: var(--success);
  background: rgba(74, 222, 128, 0.15);
  color: transparent;
}

.stepper-item.done .stepper-num::after {
  content: "✓";
  position: absolute;
  color: var(--success);
  font-size: 0.85rem;
}

.stepper-item:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

@media (max-width: 640px) {
  .stepper {
    justify-content: flex-start;
  }
  .stepper-item {
    min-width: 4rem;
    flex: 0 0 auto;
  }
}

.page-view {
  width: 100%;
}

.page-panel {
  display: none;
  flex-direction: column;
  gap: 0.75rem;
  opacity: 0;
  transform: translateY(6px);
}

.page-panel.is-active {
  display: flex;
  animation: panel-in 0.22s ease-out forwards;
}

@keyframes panel-in {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.page-nav {
  /* .layout 是两列网格，而 .page-nav 是它的第三个子元素，
     不跨列的话会被自动排到「第二行第一列」，即 PDF 左栏的正下方
     （实测：nav 与 pdfPane 的 left/right 完全一致，均为 16/536）。
     跨满所有列才能让「下一步」落在整个页面的右下角。 */
  grid-column: 1 / -1;
  display: flex;
  /* 全宽后若仍用 space-between，两个按钮会被甩到屏幕两端，跨度过大反而难点，
     因此改为成组靠右。 */
  justify-content: flex-end;
  gap: 0.75rem;
  margin-top: 0.75rem;
  padding-top: 0.65rem;
  border-top: 1px solid var(--border);
}

.page-nav .btn {
  min-width: 8rem;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem;
  box-shadow: var(--shadow-card);
  transition: background 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

/* 激活面板：更亮背景 + 蓝色边框 + 阴影 */
.page-panel.is-active.card {
  background: var(--surface-active);
  border-color: rgba(59, 130, 246, 0.4);
  box-shadow: var(--shadow-active);
}

.card h2 {
  font-size: 1.2rem;
  font-weight: 700;
  letter-spacing: -0.01em;
}

.hint-text {
  color: var(--muted);
  font-size: 0.9rem;
}

.selection-label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--muted);
  margin: 0.25rem 0 0;
}

.grade-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.btn.grade-btn,
.btn.subject-btn {
  min-width: 5.5rem;
  font-weight: 500;
}

.btn.grade-btn.is-selected,
.btn.subject-btn.is-selected {
  background: var(--accent);
  color: #fff;
  border: 2px solid #93c5fd;
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.35);
}

.btn.grade-btn.is-selected::before,
.btn.subject-btn.is-selected::before {
  content: "✓ ";
}

.grade-summary {
  margin-top: 0.5rem;
  padding: 0.85rem 1rem;
  border-radius: 10px;
  border: 1px dashed var(--border);
  background: var(--bg);
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.grade-summary.selected {
  border: 2px solid var(--accent);
  background: rgba(59, 130, 246, 0.12);
}

.grade-summary-label {
  font-size: 0.8rem;
  color: var(--muted);
}

.grade-summary-text {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text);
}

.grade-summary.selected .grade-summary-text {
  color: #dce9ff;
}

.drop-zone {
  border: 2px dashed var(--border);
  border-radius: 12px;
  padding: 1.1rem 1rem;
  text-align: center;
  transition: border-color 0.15s, background 0.15s;
}

.drop-zone.dragover {
  border-color: var(--accent);
  background: rgba(59, 130, 246, 0.08);
}

.drop-title {
  font-weight: 500;
  margin-bottom: 0.25rem;
}

.drop-hint {
  color: var(--muted);
  font-size: 0.85rem;
  margin: 0.5rem 0;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.5rem 1rem;
  border-radius: 8px;
  font-size: 0.9rem;
  cursor: pointer;
  border: none;
  font-family: inherit;
}

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

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

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

.btn-secondary {
  background: var(--surface);
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  border-color: var(--accent);
}

.action-row {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  flex-wrap: wrap;
}

.file-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.file-item {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.5rem;
  padding: 0.6rem 0.75rem;
  background: var(--surface);
  border-radius: 8px;
  border: 1px solid var(--border);
  font-size: 0.85rem;
}

.file-item .name {
  word-break: break-all;
  flex: 1;
}

.file-item .meta {
  color: var(--muted);
  font-size: 0.75rem;
  margin-top: 0.15rem;
}

.file-item .remove {
  background: none;
  border: none;
  color: var(--muted);
  cursor: pointer;
  padding: 0.15rem;
  font-size: 1.1rem;
  line-height: 1;
}

.file-item .remove:hover {
  color: var(--error);
}

.file-item.uploading {
  opacity: 0.7;
}

.btn-icon {
  width: 2.5rem;
  height: 2.5rem;
  padding: 0;
  font-size: 1.1rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
}

.btn-icon:hover {
  border-color: var(--accent);
}

.btn-icon.recording {
  background: rgba(248, 113, 113, 0.2);
  border-color: var(--error);
  animation: pulse 1s ease-in-out infinite;
}

@keyframes pulse {
  50% {
    opacity: 0.7;
  }
}

.content-box,
.quiz-box {
  min-height: 56px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--bg);
  padding: 0.75rem;
  white-space: pre-wrap;
  line-height: 1.55;
}

.unlock-badge {
  border-radius: 999px;
  padding: 0.15rem 0.6rem;
  font-size: 0.8rem;
  border: 1px solid var(--border);
}

.unlock-badge.locked {
  color: var(--muted);
}

.unlock-badge.unlocked {
  color: var(--success);
  border-color: rgba(74, 222, 128, 0.35);
  background: rgba(74, 222, 128, 0.12);
}

.question-card {
  display: flex;
  flex-direction: column;
  gap: 0.7rem;
}

.question-meta {
  font-size: 0.85rem;
  color: var(--muted);
}

.question-title {
  font-size: 0.95rem;
}

.options-list {
  margin-left: 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}

.answer-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.5rem;
}

.answer-inline {
  display: flex;
  gap: 0.5rem;
}

.answer-inline input,
.input-inline input {
  flex: 1;
  padding: 0.55rem 0.75rem;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text);
  font-family: inherit;
}

.answer-feedback {
  font-size: 0.88rem;
}

.answer-feedback.ok {
  color: var(--success);
}

.answer-feedback.error {
  color: var(--error);
}

.input-inline {
  display: flex;
  gap: 0.5rem;
}

.permission-gate {
  position: fixed;
  inset: 0;
  z-index: 150;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(15, 20, 25, 0.88);
  padding: 1rem;
}

.permission-gate.hidden {
  display: none !important;
}

.permission-gate-box {
  width: 100%;
  max-width: 400px;
  padding: 1.5rem;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--surface);
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.permission-gate-box h3 {
  font-size: 1.1rem;
}

.permission-gate-hint {
  font-size: 0.9rem;
  color: var(--muted);
  line-height: 1.55;
}

.permission-skip {
  width: 100%;
}

.global-loading {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: center;
  pointer-events: none;
  padding: 0.6rem 1rem;
  opacity: 1;
  transition: opacity 0.2s ease;
}

.global-loading.is-hidden {
  opacity: 0;
  pointer-events: none;
}

.global-loading-box {
  display: flex;
  flex-direction: row;
  align-items: center;
  gap: 0.6rem;
  padding: 0.55rem 1.1rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.35);
  pointer-events: auto;
  transform: translateY(0);
  transition: transform 0.2s ease;
}

.global-loading.is-hidden .global-loading-box {
  transform: translateY(-8px);
}

.global-loading-text {
  font-size: 0.88rem;
  color: var(--text);
  text-align: center;
}

.spinner {
  width: 1.1rem;
  height: 1.1rem;
  border: 2px solid rgba(139, 156, 179, 0.35);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.75s linear infinite;
  flex-shrink: 0;
}

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

.modal {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  padding: 1rem;
}

.modal-content {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
  width: 100%;
  max-width: 420px;
}

.modal-content h3 {
  margin-bottom: 0.5rem;
}

.modal-hint {
  color: var(--muted);
  font-size: 0.8rem;
  margin-bottom: 1rem;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  margin-bottom: 0.85rem;
  font-size: 0.85rem;
}

.field input[type="text"],
.field input[type="password"] {
  padding: 0.55rem 0.75rem;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text);
  font-family: inherit;
}

.checkbox-field {
  flex-direction: row;
  align-items: center;
}

.modal-actions {
  display: flex;
  justify-content: flex-end;
  gap: 0.5rem;
  margin-top: 1rem;
}

.teach-chat-log {
  min-height: 140px;
  max-height: 320px;
  overflow-y: auto;
  margin: 0.5rem 0 0.75rem;
  padding: 0.75rem;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--bg);
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}

.teach-chat-placeholder {
  margin: 0;
  text-align: center;
  padding: 1rem 0.5rem;
}

.chat-bubble {
  max-width: 92%;
  padding: 0.65rem 0.85rem;
  border-radius: 10px;
  font-size: 0.9rem;
  line-height: 1.5;
  white-space: pre-wrap;
  word-break: break-word;
}

.chat-bubble.ai {
  align-self: flex-start;
  background: rgba(99, 102, 241, 0.12);
  border: 1px solid rgba(99, 102, 241, 0.25);
}

.chat-bubble.student {
  align-self: flex-end;
  background: rgba(34, 197, 94, 0.1);
  border: 1px solid rgba(34, 197, 94, 0.22);
}

.chat-meta {
  display: block;
  font-size: 0.72rem;
  color: var(--muted);
  margin-bottom: 0.25rem;
}

/* ===== 做题进度仪表盘 ===== */
.quiz-dashboard {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  padding: 0.75rem 0.9rem;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--bg);
}

.quiz-progress-track {
  width: 100%;
  height: 8px;
  border-radius: 999px;
  background: rgba(139, 156, 179, 0.2);
  overflow: hidden;
}

.quiz-progress-fill {
  height: 100%;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--accent), #60a5fa);
  transition: width 0.3s ease;
}

.quiz-stats {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.quiz-stat {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.1rem;
  flex: 1 1 4rem;
  padding: 0.35rem 0.4rem;
  border-radius: 8px;
  background: var(--surface);
  border: 1px solid var(--border);
}

.quiz-stat-label {
  font-size: 0.7rem;
  color: var(--muted);
}

.quiz-stat-value {
  font-size: 1rem;
  font-weight: 600;
}

.quiz-stat-correct .quiz-stat-value {
  color: var(--success);
}

.quiz-stat-wrong .quiz-stat-value {
  color: var(--error);
}

.quiz-stat-rate .quiz-stat-value {
  color: #dce9ff;
}

/* ===== 选项按钮状态 ===== */
.option-btn {
  position: relative;
  font-weight: 500;
}

.option-btn .opt-key {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.4rem;
  height: 1.4rem;
  border-radius: 6px;
  background: rgba(139, 156, 179, 0.15);
  font-size: 0.8rem;
  margin-right: 0.3rem;
}

.option-btn.is-correct {
  background: rgba(74, 222, 128, 0.18);
  border-color: var(--success);
  color: var(--success);
}

.option-btn.is-correct::after {
  content: " ✓";
  font-weight: 700;
}

.option-btn.is-wrong {
  background: rgba(248, 113, 113, 0.18);
  border-color: var(--error);
  color: var(--error);
}

.option-btn.is-wrong::after {
  content: " ✗";
  font-weight: 700;
}

.option-btn:disabled {
  cursor: default;
  opacity: 0.85;
}

.options-list .opt-key {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.3rem;
  height: 1.3rem;
  border-radius: 5px;
  background: rgba(59, 130, 246, 0.18);
  color: #dce9ff;
  font-size: 0.75rem;
  font-weight: 600;
  margin-right: 0.35rem;
}

/* ===== 题目操作区 ===== */
.question-actions {
  display: flex;
  justify-content: flex-end;
  margin-top: 0.25rem;
}

.next-question-btn {
  min-width: 7rem;
}

/* ===== 讲解页结构化 + Karaoke ===== */
.lesson-box {
  line-height: 1.85;
}

.lesson-heading {
  font-size: 1.05rem;
  font-weight: 700;
  color: #dce9ff;
  margin: 0.8rem 0 0.4rem;
  padding-bottom: 0.3rem;
  border-bottom: 1px solid var(--border);
}

.lesson-heading:first-child {
  margin-top: 0;
}

.lesson-paragraph {
  margin: 0.4rem 0;
}

.lesson-sentence {
  transition: background 0.2s ease, color 0.2s ease;
  border-radius: 4px;
  padding: 0 1px;
}

.lesson-sentence.is-active {
  background: rgba(59, 130, 246, 0.28);
  color: #fff;
  box-shadow: 0 0 0 1px rgba(59, 130, 246, 0.4);
}

/* 段级高亮（与音频段 1:1 对齐） */
.lesson-segment {
  transition: background 0.2s ease, color 0.2s ease;
  border-radius: 4px;
  padding: 0 1px;
}
.lesson-segment.is-active {
  background: rgba(59, 130, 246, 0.28);
  color: #fff;
  box-shadow: 0 0 0 1px rgba(59, 130, 246, 0.4);
}

/* 整篇进度条 + 时间显示 */
.lesson-progress-row {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  margin: 0.5rem 0;
}
.lesson-progress {
  flex: 1;
  accent-color: var(--accent);
  height: 6px;
  cursor: pointer;
  min-width: 0;
}
.lesson-progress:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}
.lesson-time {
  min-width: 7.5rem;
  text-align: right;
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

/* 上一段/下一段按钮 */
.btn-ghost {
  background: transparent;
  border: 1px solid var(--border);
  padding: 0.25rem 0.6rem;
  line-height: 1;
  font-size: 1rem;
  color: #dce9ff;
}
.btn-ghost:hover:not(:disabled) {
  border-color: var(--accent);
  color: #fff;
}

/* ===== 错题分析页 ===== */
.analysis-summary {
  font-size: 0.95rem;
  line-height: 1.7;
  margin-bottom: 0.6rem;
  padding: 0.6rem 0.8rem;
  border-radius: 8px;
  background: rgba(59, 130, 246, 0.08);
  border-left: 3px solid var(--accent);
}

.error-reason-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  margin-bottom: 0.8rem;
}

.error-reason-item {
  display: flex;
  align-items: flex-start;
  gap: 0.6rem;
  padding: 0.55rem 0.7rem;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--surface);
}

.error-reason-icon {
  font-size: 1.1rem;
  line-height: 1.4;
  flex-shrink: 0;
}

.error-reason-body {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}

.error-reason-tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.1rem 0.45rem;
  border-radius: 4px;
  align-self: flex-start;
}

.error-reason-detail {
  font-size: 0.85rem;
  color: var(--text);
  line-height: 1.5;
}

.err-careless .error-reason-tag {
  background: rgba(251, 191, 36, 0.18);
  color: #fbbf24;
}

.err-knowledge .error-reason-tag,
.err-concept .error-reason-tag {
  background: rgba(248, 113, 113, 0.18);
  color: var(--error);
}

.err-reading .error-reason-tag {
  background: rgba(251, 146, 60, 0.18);
  color: #fb923c;
}

.err-calc .error-reason-tag {
  background: rgba(168, 85, 247, 0.18);
  color: #c084fc;
}

.err-other .error-reason-tag {
  background: rgba(139, 156, 179, 0.18);
  color: var(--muted);
}

/* ===== 空状态 ===== */
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  padding: 1.25rem 1rem;
  text-align: center;
}

.empty-state-icon {
  width: 2.4rem;
  height: 2.4rem;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: rgba(59, 130, 246, 0.1);
  color: var(--accent);
  margin-bottom: 0.2rem;
}

.empty-state-title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text);
}

.empty-state-desc {
  font-size: 0.85rem;
  color: var(--muted);
  line-height: 1.5;
  max-width: 18rem;
}

.wrong-question-list {
  margin-top: 0.6rem;
}

.wrong-list-title {
  font-size: 0.9rem;
  color: #dce9ff;
  margin: 0.4rem 0;
}

.wrong-question-item {
  display: flex;
  gap: 0.5rem;
  padding: 0.5rem 0.6rem;
  border-radius: 8px;
  background: var(--bg);
  border: 1px solid var(--border);
  margin-bottom: 0.4rem;
}

.wrong-q-index {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 1.4rem;
  height: 1.4rem;
  border-radius: 50%;
  background: rgba(248, 113, 113, 0.2);
  color: var(--error);
  font-size: 0.75rem;
  font-weight: 600;
  flex-shrink: 0;
}

.wrong-q-body {
  flex: 1;
  min-width: 0;
}

.wrong-q-text {
  font-size: 0.85rem;
  line-height: 1.5;
  margin-bottom: 0.25rem;
}

.wrong-q-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem 0.8rem;
  font-size: 0.75rem;
  color: var(--muted);
}

.wrong-q-kp {
  color: #93c5fd;
}

.wrong-user-ans {
  color: var(--error);
  font-weight: 500;
}

.wrong-correct-ans {
  color: var(--success);
  font-weight: 500;
}

.variant-related {
  font-size: 0.78rem;
  color: var(--muted);
  padding: 0.35rem 0.6rem;
  margin-bottom: 0.4rem;
  border-radius: 6px;
  background: rgba(251, 191, 36, 0.08);
  border-left: 3px solid #fbbf24;
}

/* ===== 讲题页 ===== */
.teach-guide {
  margin: 0.6rem 0;
  padding: 0.5rem 0.8rem;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: rgba(59, 130, 246, 0.06);
}

.teach-guide summary {
  cursor: pointer;
  font-size: 0.85rem;
  color: #93c5fd;
  font-weight: 500;
  user-select: none;
}

.teach-guide-list {
  margin: 0.5rem 0 0;
  padding-left: 1.2rem;
  font-size: 0.82rem;
  line-height: 1.7;
  color: var(--text);
}

.teach-guide-list li {
  margin-bottom: 0.2rem;
}

.teach-guide-list strong {
  color: #dce9ff;
}

.recording-panel {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.5rem 0.7rem;
  margin: 0.5rem 0;
  border-radius: 8px;
  border: 1px solid rgba(248, 113, 113, 0.3);
  background: rgba(248, 113, 113, 0.06);
}

#waveformCanvas {
  flex: 1;
  max-width: 100%;
  height: 40px;
  display: block;
}

.recording-timer {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--error);
  font-variant-numeric: tabular-nums;
  flex-shrink: 0;
}

/* 录制状态：红点闪烁 + 文字，让「正在录制」一眼可辨 */
.recording-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--error);
  flex-shrink: 0;
  animation: recording-blink 1s ease-in-out infinite;
}

@keyframes recording-blink {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.25; }
}

@media (prefers-reduced-motion: reduce) {
  .recording-dot { animation: none; }
}

.recording-status {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--error);
  flex-shrink: 0;
}

/* 录制中的按钮用醒目的红色，与「开始录制」的次要色形成对比 */
.btn-danger {
  background: var(--error);
  border-color: var(--error);
  color: #fff;
}

.btn-danger:hover:not(:disabled) {
  filter: brightness(0.93);
}

.teach-record-row,
.teach-audio-bar {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  flex-wrap: wrap;
  margin: 0.5rem 0;
}

.mic-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  padding: 0;
  flex-shrink: 0;
}

.mic-btn .mic-icon {
  display: block;
}

.mic-btn.recording {
  background: rgba(248, 113, 113, 0.2);
  border-color: var(--error);
  color: var(--error);
  animation: mic-pulse 1.2s ease-in-out infinite;
}

@keyframes mic-pulse {
  0%, 100% {
    box-shadow: 0 0 0 0 rgba(248, 113, 113, 0.4);
  }
  50% {
    box-shadow: 0 0 0 6px rgba(248, 113, 113, 0);
  }
}