:root {
  --blue: #2563eb;
  --blue-dark: #1d4ed8;
  --green: #16a34a;
  --red: #dc2626;
  --orange: #f59e0b;
  --ink: #172033;
  --muted: #64748b;
  --line: #dbe3ef;
  --bg: #f4f7fb;
  --card: #ffffff;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  background: var(--bg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", sans-serif;
}

button,
select {
  font: inherit;
}

.app-shell {
  width: 100%;
  max-width: 640px;
  min-height: 100vh;
  margin: 0 auto;
  background: linear-gradient(180deg, #eef5ff 0, #f8fafc 180px, #f8fafc 100%);
}

.app-header {
  position: sticky;
  top: 0;
  z-index: 2;
  display: flex;
  gap: 12px;
  align-items: center;
  padding: 18px 18px 12px;
  background: rgba(248, 250, 252, 0.92);
  border-bottom: 1px solid rgba(219, 227, 239, 0.75);
  backdrop-filter: blur(12px);
}

.app-header h1 {
  margin: 2px 0 0;
  font-size: 22px;
  line-height: 1.25;
}

.eyebrow {
  margin: 0;
  color: var(--blue);
  font-size: 12px;
  font-weight: 700;
}

.app-main {
  padding: 16px;
}

.hidden {
  display: none !important;
}

.icon-button {
  flex: 0 0 38px;
  width: 38px;
  height: 38px;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--blue);
  background: var(--card);
  font-size: 30px;
  line-height: 30px;
}

.hero,
.home-hero {
  padding: 18px;
  border-radius: 8px;
  color: #ffffff;
  background: linear-gradient(135deg, #2563eb, #0f766e);
}

.home-hero {
  padding: 22px;
  border-radius: 12px;
  background: linear-gradient(135deg, #1d4ed8 0%, #0f766e 100%);
  box-shadow: 0 14px 30px rgba(37, 99, 235, 0.22);
}

.hero h2,
.home-hero h2 {
  margin: 0;
  font-size: 26px;
  line-height: 1.25;
}

.hero p,
.home-hero p {
  margin: 8px 0 0;
  color: rgba(255, 255, 255, 0.88);
}

.home-hero .eyebrow {
  color: rgba(255, 255, 255, 0.86);
}

.dashboard-card {
  margin-top: 14px;
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #ffffff;
  box-shadow: 0 12px 28px rgba(30, 41, 59, 0.07);
}

.dashboard-head,
.coverage-row {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: center;
}

.dashboard-head h3 {
  margin: 0;
  font-size: 18px;
}

.dashboard-head span,
.coverage-row span {
  color: var(--muted);
  font-size: 13px;
}

.metric-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
  margin: 14px 0;
}

.metric-item {
  padding: 12px 8px;
  border-radius: 10px;
  background: #f8fafc;
  text-align: center;
}

.metric-item strong {
  display: block;
  font-size: 24px;
  line-height: 1.1;
}

.metric-item span {
  display: block;
  margin-top: 5px;
  color: var(--muted);
  font-size: 12px;
}

.metric-item.blue strong { color: var(--blue); }
.metric-item.green strong { color: var(--green); }
.metric-item.red strong { color: var(--red); }
.metric-item.gold strong { color: #ca8a04; }

.compact-metrics {
  grid-template-columns: repeat(4, 1fr);
}

.learning-feedback {
  border-left: 4px solid #2563eb;
}

.recommendation-card {
  border-left: 5px solid #16a34a;
}

.recommendation-list {
  display: grid;
  gap: 8px;
  margin: 8px 0 12px;
}

.recommendation-row {
  padding: 10px;
  border: 1px solid #bbf7d0;
  border-radius: 8px;
  background: #f0fdf4;
}

.recommendation-row strong,
.recommendation-row span {
  display: block;
}

.recommendation-row span {
  margin-top: 4px;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.45;
}

.mini-list {
  display: grid;
  gap: 8px;
  margin-top: 10px;
}

.knowledge-row {
  display: grid;
  grid-template-columns: 1fr auto auto;
  gap: 8px;
  align-items: center;
  padding: 10px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #f8fafc;
}

.knowledge-row strong,
.knowledge-row span {
  display: block;
}

.knowledge-row div span {
  margin-top: 3px;
  color: var(--muted);
  font-size: 13px;
}

.compact-button {
  min-height: 32px;
  padding: 6px 10px;
  white-space: nowrap;
}

.coverage-row strong {
  display: block;
  font-size: 18px;
}

.progress-track {
  height: 9px;
  margin-top: 8px;
  border-radius: 999px;
  overflow: hidden;
  background: #e2e8f0;
}

.progress-track div {
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, #2563eb, #14b8a6);
}

.primary-actions {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
  margin-top: 16px;
}

.feature-card {
  position: relative;
  min-height: 166px;
  padding: 18px;
  border-radius: 14px;
  color: #ffffff;
  overflow: hidden;
  box-shadow: 0 16px 34px rgba(30, 41, 59, 0.15);
}

.feature-card.chapter {
  background: linear-gradient(135deg, #1d4ed8, #0f766e);
}

.feature-card.random {
  background: linear-gradient(135deg, #7c3aed, #f97316);
}

.feature-card.scenario {
  background: linear-gradient(135deg, #0e7490, #4338ca);
}

.feature-card h3 {
  margin: 6px 0 6px;
  font-size: 22px;
}

.feature-card p {
  margin: 0 0 16px;
  color: rgba(255, 255, 255, 0.88);
}

.feature-icon {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  display: grid;
  place-items: center;
  background: rgba(255, 255, 255, 0.18);
  font-weight: 900;
}

.feature-button {
  width: auto;
  min-height: 40px;
  padding: 0 14px;
  border: 0;
  border-radius: 8px;
  color: #0f172a;
  background: #ffffff;
  font-weight: 800;
}

.scenario-card {
  margin: 14px 0;
  padding: 14px;
  border: 1px solid #bae6fd;
  border-left: 5px solid #0891b2;
  border-radius: 12px;
  background: #f0f9ff;
}

.scenario-card h3 {
  margin: 0 0 8px;
  color: #0f172a;
}

.scenario-card p,
.scenario-snippet {
  white-space: pre-wrap;
  line-height: 1.7;
}

.scenario-list-card {
  border-left: 5px solid #0891b2;
}

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

.support-card {
  min-height: 92px;
  padding: 13px;
  border: 1px solid transparent;
  border-radius: 12px;
  text-align: left;
  color: var(--ink);
  background: #ffffff;
  box-shadow: 0 8px 20px rgba(30, 41, 59, 0.06);
}

.support-card strong {
  display: block;
  font-size: 16px;
}

.support-card span {
  display: block;
  margin-top: 6px;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.35;
}

.support-card.wrong { border-color: #fecaca; background: #fff7f7; }
.support-card.favorite { border-color: #fde68a; background: #fffbeb; }
.support-card.progress { border-color: #bbf7d0; background: #f0fdf4; }
.support-card.formulas { border-color: #ddd6fe; background: #f5f3ff; }

.teacher-link {
  display: block;
  margin: 22px auto 4px;
  border: 0;
  color: #94a3b8;
  background: transparent;
  font-size: 12px;
  text-decoration: underline;
}

.version-text {
  margin: 18px 0 0;
  color: #94a3b8;
  font-size: 12px;
  text-align: center;
}

.version-status {
  margin: 18px auto 0;
  max-width: 520px;
  color: #64748b;
  font-size: 12px;
  line-height: 1.5;
  text-align: center;
}

.version-status p {
  margin: 0;
}

.version-status .status-warning {
  margin-top: 6px;
  color: #b45309;
}

.home-info-card {
  margin-top: 14px;
  padding: 15px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #ffffff;
  box-shadow: 0 10px 24px rgba(30, 41, 59, 0.06);
}

.home-info-card h3 {
  margin: 0 0 7px;
  font-size: 17px;
}

.home-info-card p {
  margin: 0 0 12px;
  color: var(--muted);
  line-height: 1.55;
}

.continue-card {
  border-left: 5px solid #14b8a6;
}

.advice-card {
  border-left: 5px solid #f59e0b;
}

.random-count {
  border-left: 5px solid #7c3aed;
}

.random-count.recommended {
  border-color: #f97316;
  background: #fff7ed;
}

.random-settings {
  display: grid;
  gap: 14px;
}

.quick-scope-row,
.random-count-row,
.filter-chip-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.quick-scope-row .ghost-button {
  flex: 1 1 180px;
  text-align: left;
}

.quick-scope-row .ghost-button.active {
  color: #ffffff;
  border-color: var(--blue);
  background: var(--blue);
  font-weight: 700;
}

.check-row,
.filter-chip-grid label,
.random-count-option {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.scope-tree {
  display: grid;
  gap: 12px;
}

.scope-book {
  border: 1px solid #e2e8f0;
  border-radius: 8px;
  background: #f8fafc;
  padding: 10px;
}

.scope-chapters {
  display: grid;
  gap: 6px;
  margin-top: 8px;
}

.scope-chapters summary {
  cursor: pointer;
}

.scope-sections {
  display: grid;
  gap: 6px;
  margin: 8px 0 4px 22px;
}

.random-count-option,
.filter-chip-grid label {
  border: 1px solid #dbeafe;
  border-radius: 10px;
  background: #ffffff;
  padding: 10px;
}

.random-count-option {
  flex: 1 1 120px;
  flex-direction: column;
  align-items: flex-start;
}

.random-count-option.recommended {
  border-color: #60a5fa;
  background: #eff6ff;
}

.random-available {
  display: grid;
  gap: 4px;
  border: 1px solid #bae6fd;
  border-radius: 8px;
  background: #f0f9ff;
  padding: 12px;
}

.wrong-tabs {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 7px;
  margin-bottom: 12px;
}

.wrong-tabs button {
  min-height: 38px;
  padding: 8px 6px;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--muted);
  background: #ffffff;
  font-size: 13px;
  font-weight: 700;
}

.wrong-tabs button.active {
  color: #ffffff;
  background: var(--blue);
  border-color: var(--blue);
}

.blank-list {
  display: grid;
  gap: 10px;
}

.blank-row {
  display: grid;
  gap: 6px;
  color: var(--muted);
  font-size: 14px;
}

.blank-row input,
.short-answer {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 12px;
  color: var(--ink);
  background: #ffffff;
  font: inherit;
}

.blank-symbol-panel {
  margin-top: 12px;
  padding: 10px;
  border: 1px solid #dbeafe;
  border-radius: 10px;
  background: #f8fbff;
}

.blank-symbol-title {
  margin-bottom: 8px;
  color: var(--muted);
  font-size: 13px;
  font-weight: 800;
}

.blank-symbol-row {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding-bottom: 2px;
  -webkit-overflow-scrolling: touch;
}

.symbol-button {
  flex: 0 0 auto;
  min-width: 44px;
  min-height: 36px;
  border: 1px solid #bfdbfe;
  border-radius: 8px;
  color: #1e3a8a;
  background: #ffffff;
  font-weight: 800;
}

.short-answer {
  min-height: 132px;
  resize: vertical;
  line-height: 1.55;
}

.result-status.pending {
  border-left-color: #7c3aed;
  background: #f3efff;
}

.result-status.pending strong {
  color: #6d28d9;
}

.wrong-summary {
  padding: 12px;
  border: 1px solid var(--line);
  border-left: 5px solid var(--red);
  border-radius: 10px;
  background: #fffafa;
}

.wrong-summary p {
  margin: 7px 0;
  color: var(--muted);
  line-height: 1.5;
}

.teacher-warning {
  margin-top: 12px;
  padding: 12px;
  border: 1px solid #fed7aa;
  border-left: 5px solid var(--orange);
  border-radius: 10px;
  background: #fff7ed;
  color: #7c2d12;
}

.teacher-warning p {
  margin: 8px 0 0;
  line-height: 1.5;
}

.teacher-hero {
  padding: 16px;
  border-radius: 12px;
  color: #ffffff;
  background: linear-gradient(135deg, #334155, #111827);
}

.teacher-hero h2 {
  margin: 0 0 6px;
}

.teacher-hero p {
  margin: 0;
  color: rgba(255, 255, 255, 0.82);
}

.teacher-actions {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 8px;
  margin-top: 12px;
}

.danger-zone {
  border-color: #fecaca;
}

.stats-grid,
.menu-grid,
.progress-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
  margin-top: 14px;
}

.stat-card,
.card,
.question-card,
.feedback,
.formula-card {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--card);
  box-shadow: 0 8px 22px rgba(30, 41, 59, 0.05);
}

.stat-card {
  padding: 13px;
}

.stat-card strong {
  display: block;
  font-size: 24px;
}

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

.menu-button,
.primary-button,
.secondary-button,
.danger-button,
.option-button,
.ghost-button {
  width: 100%;
  min-height: 44px;
  border-radius: 8px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.12s ease, border-color 0.12s ease, background 0.12s ease;
}

.menu-button {
  padding: 14px 12px;
  color: var(--ink);
  background: var(--card);
  border-color: var(--line);
  text-align: left;
  font-weight: 700;
}

.menu-button small {
  display: block;
  margin-top: 4px;
  color: var(--muted);
  font-weight: 500;
}

.primary-button {
  color: #ffffff;
  background: var(--blue);
  font-weight: 700;
}

.secondary-button {
  color: var(--blue);
  background: #eef5ff;
  border-color: #bfdbfe;
  font-weight: 700;
}

.danger-button {
  color: #ffffff;
  background: var(--red);
  font-weight: 700;
}

.ghost-button {
  color: var(--ink);
  background: #ffffff;
  border-color: var(--line);
}

.menu-button:active,
.primary-button:active,
.secondary-button:active,
.danger-button:active,
.option-button:active,
.ghost-button:active {
  transform: scale(0.99);
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
  transform: none;
}

.section-title {
  margin: 20px 0 10px;
  font-size: 18px;
}

.list {
  display: grid;
  gap: 10px;
}

.card,
.formula-card {
  padding: 14px;
}

.card h3,
.formula-card h3 {
  margin: 0 0 8px;
  font-size: 16px;
}

.card p,
.formula-card p {
  margin: 6px 0;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.55;
}

.pill-row {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 8px;
}

.pill {
  padding: 4px 8px;
  border-radius: 999px;
  color: var(--blue-dark);
  background: #dbeafe;
  font-size: 12px;
  font-weight: 700;
}

.inline-alert {
  margin: 10px 0 0;
  color: var(--red);
  font-size: 14px;
  font-weight: 700;
}

.muted-text {
  color: var(--muted);
  font-size: 14px;
  line-height: 1.55;
}

.check-row,
.file-row {
  display: flex;
  align-items: center;
  gap: 8px;
  min-height: 42px;
  padding: 10px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #ffffff;
  color: var(--ink);
  font-size: 14px;
}

.file-row {
  justify-content: space-between;
  margin-top: 10px;
  flex-wrap: wrap;
}

.file-row input {
  max-width: 100%;
}

.template-links {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 8px;
  margin: 10px 0 12px;
}

.template-links a {
  display: block;
  min-height: 40px;
  padding: 10px;
  border: 1px solid #bfdbfe;
  border-radius: 8px;
  color: var(--blue);
  background: #eef5ff;
  text-align: center;
  text-decoration: none;
  font-weight: 700;
  font-size: 14px;
}

.modal-backdrop {
  position: fixed;
  inset: 0;
  z-index: 20;
  display: grid;
  place-items: center;
  padding: 18px;
  background: rgba(15, 23, 42, 0.42);
}

.modal-card {
  width: min(100%, 420px);
  padding: 18px;
  border-radius: 8px;
  background: #ffffff;
  box-shadow: 0 18px 48px rgba(15, 23, 42, 0.22);
}

.modal-card h3 {
  margin: 0 0 8px;
  font-size: 18px;
}

.modal-card p {
  margin: 0 0 14px;
  color: var(--muted);
}

.toolbar {
  display: flex;
  gap: 8px;
  margin: 12px 0;
}

.toolbar > * {
  flex: 1;
}

.page-nav {
  display: flex;
  gap: 8px;
  align-items: center;
  margin: 0 0 12px;
}

.page-nav .nav-button {
  flex: 1;
  min-height: 40px;
  padding: 8px 10px;
  font-size: 14px;
}

.select {
  width: 100%;
  min-height: 42px;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--ink);
  background: #ffffff;
  padding: 0 10px;
}

.question-card {
  padding: 16px;
}

.question-meta {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  color: var(--muted);
  font-size: 13px;
}

.question-card h2 {
  margin: 14px 0;
  font-size: 19px;
  line-height: 1.45;
}

.options {
  display: grid;
  gap: 9px;
}

.option-button {
  display: flex;
  align-items: flex-start;
  gap: 9px;
  padding: 12px;
  color: var(--ink);
  background: #ffffff;
  border-color: var(--line);
  text-align: left;
  line-height: 1.45;
}

.option-button.selected {
  border-color: var(--blue);
  background: #eff6ff;
}

.option-button.correct {
  border-color: var(--green);
  background: #ecfdf3;
}

.option-button.wrong {
  border-color: var(--red);
  background: #fef2f2;
}

.option-letter {
  flex: 0 0 24px;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  color: #ffffff;
  background: var(--blue);
  text-align: center;
  font-weight: 800;
  line-height: 24px;
}

.quiz-actions {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-top: 14px;
}

.feedback {
  margin-top: 12px;
  padding: 13px;
  border-left: 4px solid var(--orange);
}

.feedback.good {
  border-left-color: var(--green);
}

.feedback.bad {
  border-left-color: var(--red);
}

.feedback h3 {
  margin: 0 0 8px;
  font-size: 16px;
}

.feedback p {
  margin: 7px 0;
  color: var(--muted);
  line-height: 1.55;
}

.result-panel {
  display: grid;
  gap: 10px;
  margin-top: 12px;
}

.result-status,
.feedback-block {
  border: 1px solid var(--line);
  border-left: 5px solid var(--blue);
  border-radius: 10px;
  padding: 13px;
  background: #ffffff;
  box-shadow: 0 8px 18px rgba(30, 41, 59, 0.05);
}

.result-status {
  display: grid;
  gap: 4px;
}

.result-status strong {
  font-size: 18px;
}

.result-status span {
  color: var(--muted);
  font-size: 14px;
}

.result-status.correct {
  border-left-color: #20a05a;
  background: #e8f7ee;
}

.result-status.correct strong {
  color: #15803d;
}

.result-status.wrong {
  border-left-color: #d64545;
  background: #fdecec;
}

.result-status.wrong strong {
  color: #b91c1c;
}

.feedback-block.answer {
  border-left-color: #2f9e44;
  background: #eef7ee;
}

.feedback-block.explanation {
  border-left-color: #3b82f6;
  background: #eef4ff;
}

.feedback-block.knowledge {
  border-left-color: #7c3aed;
  background: #f3efff;
}

.feedback-block.mistake {
  border-left-color: #f59e0b;
  background: #fff6e8;
}

.feedback-block.option-explanations {
  border-left-color: #0ea5e9;
  background: #f8fafc;
}

.feedback-block.common-wrong {
  border-left-color: #fb923c;
  background: #fff7ed;
}

.option-explanation-list,
.common-wrong-list {
  display: grid;
  gap: 10px;
}

.option-explanation-row {
  border: 1px solid #e5e7eb;
  border-radius: 8px;
  padding: 10px;
  background: #ffffff;
}

.option-explanation-row p {
  margin: 6px 0 0;
  line-height: 1.65;
}

.option-explanation-head {
  display: flex;
  align-items: center;
  gap: 8px;
}

.option-explanation-head strong {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  border-radius: 999px;
  background: #e5e7eb;
}

.option-explanation-head span {
  font-weight: 700;
  font-size: 0.9rem;
}

.option-explanation-row.chosen-correct {
  border-color: #86efac;
  background: #f0fdf4;
}

.option-explanation-row.chosen-correct .option-explanation-head strong {
  color: #166534;
  background: #bbf7d0;
}

.option-explanation-row.chosen-wrong {
  border-color: #fecaca;
  background: #fff1f2;
}

.option-explanation-row.chosen-wrong .option-explanation-head strong {
  color: #991b1b;
  background: #fecaca;
}

.option-explanation-row.missed-correct {
  border-color: #bfdbfe;
  background: #eff6ff;
}

.option-explanation-row.missed-correct .option-explanation-head strong {
  color: #1d4ed8;
  background: #dbeafe;
}

.feedback-title {
  margin-bottom: 6px;
  color: var(--ink);
  font-size: 15px;
  font-weight: 800;
}

.feedback-content {
  color: #334155;
  font-size: 15px;
  line-height: 1.65;
}

.empty {
  padding: 32px 16px;
  color: var(--muted);
  text-align: center;
}

.status-good {
  color: var(--green);
  font-weight: 800;
}

.status-mid {
  color: var(--orange);
  font-weight: 800;
}

.status-bad {
  color: var(--red);
  font-weight: 800;
}

@media (min-width: 700px) {
  body {
    padding: 20px 0;
  }

  .app-shell {
    min-height: calc(100vh - 40px);
    border: 1px solid var(--line);
    border-radius: 12px;
    overflow: hidden;
  }

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

@media (max-width: 420px) {
  .random-settings {
    gap: 10px;
  }

  .random-settings h3 {
    margin: 6px 0 0;
    font-size: 16px;
  }

  .quick-scope-row,
  .random-count-row,
  .filter-chip-grid {
    gap: 6px;
  }

  .quick-scope-row .ghost-button,
  .random-count-option,
  .filter-chip-grid label {
    flex-basis: 100%;
    min-height: 40px;
    padding: 9px 10px;
  }

  .scope-book {
    padding: 9px;
  }

  .scope-chapters {
    gap: 4px;
  }

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

  .knowledge-row {
    grid-template-columns: 1fr;
    align-items: stretch;
  }

  .compact-button {
    width: 100%;
  }

  .teacher-actions {
    grid-template-columns: 1fr;
  }
}