:root {
  --primary-start: #667eea;
  --primary-end: #764ba2;
  --bg: #f5f7fb;
  --text: #1f2937;
  --muted: #6b7280;
  --border: #e5e7eb;
  --card: #ffffff;
  --danger: #ef4444;
  --success: #22c55e;
  --green: #4caf50;
  --yellow: #ffc107;
  --blue: #2196f3;
  --orange: #ff9800;
  --purple: #8b5cf6;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "PingFang SC", "Microsoft YaHei", sans-serif;
  background: linear-gradient(180deg, #eef2ff 0%, var(--bg) 22%, var(--bg) 100%);
  color: var(--text);
}

a {
  color: inherit;
  text-decoration: none;
}

button,
input,
textarea,
select {
  font: inherit;
}

button {
  cursor: pointer;
}

.page {
  max-width: 480px;
  min-height: 100vh;
  margin: 0 auto;
  padding: 16px;
}

.page-wide {
  max-width: 1120px;
}

.card {
  background: var(--card);
  border-radius: 18px;
  padding: 18px;
  box-shadow: 0 10px 30px rgba(102, 126, 234, 0.08);
  margin-bottom: 16px;
}

.hero {
  background: linear-gradient(135deg, var(--primary-start), var(--primary-end));
  color: #fff;
}

.title {
  font-size: 20px;
  font-weight: 700;
  margin: 0 0 8px;
}

.subtitle,
.hint,
.empty,
.small-text {
  color: var(--muted);
  font-size: 14px;
  line-height: 1.6;
}

.hero .subtitle,
.hero .small-text {
  color: rgba(255, 255, 255, 0.88);
}

.form-group {
  margin-bottom: 14px;
}

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

.input,
.textarea,
.select,
.btn {
  width: 100%;
  min-height: 44px;
  border-radius: 14px;
  border: 1px solid var(--border);
}

.input,
.textarea,
.select {
  padding: 12px 14px;
  background: #fff;
}

.textarea {
  min-height: 120px;
  resize: vertical;
  line-height: 1.6;
}

.btn {
  border: none;
  padding: 12px 16px;
  font-weight: 600;
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.btn:disabled {
  opacity: 0.65;
  cursor: not-allowed;
}

.btn-primary {
  color: #fff;
  background: linear-gradient(135deg, var(--primary-start), var(--primary-end));
}

.btn-secondary {
  background: #eef2ff;
  color: #4338ca;
}

.btn-danger {
  background: #fee2e2;
  color: #b91c1c;
}

.btn-outline {
  background: #fff;
  border: 1px solid var(--border);
  color: var(--text);
}

.btn-inline {
  width: auto;
  min-width: 96px;
}

.row {
  display: flex;
  gap: 12px;
}

.row > * {
  flex: 1;
}

.link-btn {
  border: none;
  background: transparent;
  color: var(--primary-start);
  padding: 0;
}

.error-box,
.success-box,
.info-box {
  border-radius: 14px;
  padding: 12px 14px;
  margin-bottom: 14px;
  font-size: 14px;
  line-height: 1.5;
}

.error-box {
  background: #fee2e2;
  color: #b91c1c;
}

.success-box {
  background: #dcfce7;
  color: #166534;
}

.info-box {
  background: #eef2ff;
  color: #4338ca;
}

.hidden {
  display: none !important;
}

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

.header-title {
  font-size: 18px;
  font-weight: 700;
  margin: 0;
}

.icon-btn,
.back-link {
  width: 40px;
  height: 40px;
  border-radius: 12px;
  border: none;
  background: #fff;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 8px 20px rgba(15, 23, 42, 0.08);
}

.color-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.color-card {
  border: 2px solid transparent;
  border-radius: 16px;
  padding: 14px;
  background: #fff;
  box-shadow: 0 8px 18px rgba(15, 23, 42, 0.05);
}

.color-card.active.green { border-color: var(--green); }
.color-card.active.yellow { border-color: var(--yellow); }
.color-card.active.blue { border-color: var(--blue); }
.color-card.active.orange { border-color: var(--orange); }

.color-card small {
  display: block;
  color: var(--muted);
  margin-top: 6px;
  line-height: 1.5;
}

.function-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

.function-card {
  padding: 18px 16px;
  border-radius: 18px;
  background: #fff;
  box-shadow: 0 10px 24px rgba(15, 23, 42, 0.08);
}

.function-card h3,
.function-card p,
.record-card h4,
.record-card p {
  margin: 0;
}

.function-card h3,
.record-card h4 {
  margin-bottom: 8px;
  font-size: 16px;
}

.function-card p,
.record-card p {
  color: var(--muted);
  font-size: 14px;
  line-height: 1.6;
}

.tag {
  display: inline-flex;
  align-items: center;
  padding: 4px 10px;
  border-radius: 999px;
  font-size: 12px;
  font-weight: 600;
}

.tag.green { background: rgba(76, 175, 80, 0.15); color: var(--green); }
.tag.yellow { background: rgba(255, 193, 7, 0.18); color: #b7791f; }
.tag.blue { background: rgba(33, 150, 243, 0.14); color: var(--blue); }
.tag.orange { background: rgba(255, 152, 0, 0.16); color: var(--orange); }
.tag.ambr { background: rgba(139, 92, 246, 0.14); color: var(--purple); }
.tag.talk { background: rgba(33, 150, 243, 0.14); color: var(--blue); }
.tag.nature { background: rgba(76, 175, 80, 0.14); color: var(--green); }

.result-card {
  background: #fff;
  border-radius: 18px;
  padding: 16px;
  box-shadow: 0 10px 30px rgba(15, 23, 42, 0.08);
}

.markdown {
  font-size: 15px;
  line-height: 1.7;
}

.markdown h3,
.markdown h4 {
  margin: 14px 0 8px;
}

.markdown ul {
  padding-left: 20px;
  margin: 8px 0;
}

.markdown p {
  margin: 8px 0;
}

.tabs {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  margin-bottom: 16px;
}

.tab-btn {
  flex: 1;
  min-width: 84px;
  height: 40px;
  border: none;
  border-radius: 999px;
  background: #fff;
  color: var(--muted);
  font-weight: 600;
}

.tab-btn.active {
  background: linear-gradient(135deg, var(--primary-start), var(--primary-end));
  color: #fff;
}

.record-card {
  background: #fff;
  border-radius: 18px;
  padding: 16px;
  box-shadow: 0 10px 24px rgba(15, 23, 42, 0.08);
  margin-bottom: 12px;
}

.record-top,
.record-meta,
.action-row,
.space-between {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.align-start {
  align-items: flex-start;
}

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

.admin-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.panel-box {
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 16px;
  background: #fff;
}

.section-title {
  margin: 0 0 12px;
  font-size: 16px;
}

.filter-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}

.checkbox-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.checkbox-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  color: var(--text);
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(6, minmax(0, 1fr));
  gap: 12px;
}

.stat-card {
  border-radius: 16px;
  background: #fff;
  border: 1px solid var(--border);
  padding: 14px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.stat-card strong {
  font-size: 22px;
}

.stat-card span {
  color: var(--muted);
  font-size: 13px;
}

.pagination-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  margin-top: 16px;
}

.code-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 10px;
}

.code-list code {
  display: inline-flex;
  padding: 6px 10px;
  border-radius: 10px;
  background: #eef2ff;
  color: #4338ca;
}

.record-content {
  margin-top: 12px;
  border-top: 1px solid var(--border);
  padding-top: 12px;
}

.knowledge-section p {
  line-height: 1.7;
}

.knowledge-grid,
.memory-grid,
.score-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.knowledge-card,
.memory-card,
.tip-item {
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 16px;
  background: #fff;
}

.knowledge-card h4,
.memory-card p,
.tip-item p,
.tip-item strong,
.review-item p,
.review-item strong {
  margin: 0;
}

.knowledge-card h4,
.memory-card strong,
.tip-item strong,
.review-item strong {
  display: block;
  margin-top: 10px;
  margin-bottom: 8px;
  font-size: 16px;
}

.knowledge-card p,
.memory-card p,
.tip-item p,
.review-item p {
  color: var(--muted);
  line-height: 1.7;
  font-size: 14px;
}

.border-green { border-color: rgba(76, 175, 80, 0.35); }
.border-yellow { border-color: rgba(255, 193, 7, 0.45); }
.border-blue { border-color: rgba(33, 150, 243, 0.35); }
.border-orange { border-color: rgba(255, 152, 0, 0.4); }

.tips-list,
.review-list,
.question-list {
  display: grid;
  gap: 12px;
}

.review-item {
  padding: 14px 0;
  border-bottom: 1px solid var(--border);
}

.review-item:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.review-item:first-child {
  padding-top: 0;
}

.knowledge-bullets {
  margin: 0;
  padding-left: 20px;
  color: var(--muted);
  line-height: 1.8;
}

.lecture-meta,
.chapter-header {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.chapter-header {
  align-items: center;
  margin-bottom: 12px;
}

.lecture-grid,
.guide-grid,
.case-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.lecture-box,
.summary-card,
.case-card,
.exercise-card {
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 16px;
  background: #fff;
}

.lecture-box {
  background: linear-gradient(180deg, #f8faff 0%, #ffffff 100%);
}

.summary-card {
  background: linear-gradient(180deg, #f8fafc 0%, #ffffff 100%);
}

.case-card {
  background: #fcfcff;
}

.exercise-card {
  background: #fbfbfe;
}

.lecture-box strong,
.summary-card strong,
.case-card strong,
.exercise-card strong {
  display: block;
  margin-bottom: 8px;
  font-size: 16px;
}

.lecture-box p,
.summary-card p,
.case-card p,
.exercise-card p {
  margin: 0;
  color: var(--muted);
  line-height: 1.7;
  font-size: 14px;
}

.chapter-index {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 88px;
  min-height: 30px;
  padding: 0 12px;
  border-radius: 999px;
  background: rgba(102, 126, 234, 0.12);
  color: #4f46e5;
  font-size: 13px;
  font-weight: 700;
}

.summary-strip {
  border-left: 4px solid #667eea;
  padding: 14px 16px;
  border-radius: 14px;
  background: #f7f8ff;
}

.summary-strip p {
  margin: 0;
  color: var(--text);
  line-height: 1.8;
}

.summary-strip strong {
  color: #4338ca;
}

.chapter-note {
  margin-top: 12px;
  padding: 12px 14px;
  border-radius: 14px;
  background: #fafbff;
  color: var(--muted);
  line-height: 1.7;
  font-size: 14px;
}

.question-card {
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 16px;
  background: #fff;
}

.question-title {
  margin: 12px 0;
  font-size: 15px;
  line-height: 1.7;
}

.option-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 12px 14px;
  border: 1px solid var(--border);
  border-radius: 14px;
  margin-bottom: 10px;
  background: #fafbff;
  line-height: 1.6;
}

.option-item:last-child {
  margin-bottom: 0;
}

.option-item input {
  margin-top: 4px;
}

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

.result-summary h4 {
  margin: 10px 0 8px;
  line-height: 1.6;
}

.footer-quote {
  text-align: center;
  font-size: 14px;
  color: var(--muted);
  padding: 18px 0 8px;
}

.center {
  text-align: center;
}

.mt-12 { margin-top: 12px; }
.mt-16 { margin-top: 16px; }
.mt-20 { margin-top: 20px; }
.mb-0 { margin-bottom: 0; }

@media (max-width: 420px) {
  .function-grid,
  .color-grid,
  .row {
    grid-template-columns: 1fr;
    flex-direction: column;
  }
}

@media (max-width: 900px) {
  .admin-grid,
  .stats-grid,
  .filter-grid,
  .checkbox-grid,
  .knowledge-grid,
  .memory-grid,
  .score-grid,
  .lecture-grid,
  .guide-grid,
  .case-grid {
    grid-template-columns: 1fr;
  }
}