:root {
  --primary-color: #0066cc;
  --bg-color: #f5f5f7;
  --text-color: #1d1d1f;
  --correct-color: #1a7c3e;
  --correct-bg: #e8f5e9;
  --correct-border: #a5d6a7;
  --wrong-color: #b71c1c;
  --wrong-bg: #ffebee;
  --wrong-border: #ef9a9a;
  --border-color: #d2d2d7;
  --card-bg: #ffffff;
  --exp-bg: #f2f2f7;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Helvetica Neue", "Segoe UI", "Yu Gothic", YuGothic, sans-serif;
}

body {
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.65;
  -webkit-text-size-adjust: 100%;
}

header {
  background-color: var(--card-bg);
  padding: 12px 16px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.12);
  position: sticky;
  top: 0;
  z-index: 100;
}

h1 {
  font-size: 1.1rem;
  margin-bottom: 6px;
  text-align: center;
  font-weight: 700;
  letter-spacing: -0.3px;
}

main {
  padding: 12px 16px 32px;
  max-width: 600px;
  margin: 0 auto;
}

.hidden { display: none !important; }

/* ---- Navigation ---- */

#top-nav {
  display: flex;
  gap: 8px;
  margin-top: 8px;
}

.nav-btn {
  flex: 1;
  padding: 7px;
  background: var(--exp-bg);
  border: none;
  border-radius: 6px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s;
}

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

/* ---- Home screen ---- */

.menu-btn {
  display: block;
  width: 100%;
  padding: 16px;
  margin-bottom: 12px;
  background-color: var(--card-bg);
  border: 2px solid var(--primary-color);
  color: var(--primary-color);
  border-radius: 12px;
  font-size: 1.05rem;
  font-weight: 700;
  text-align: left;
  cursor: pointer;
  transition: background 0.15s;
}

.menu-btn:active { background: #e8f0fb; }

.menu-btn small {
  display: block;
  font-size: 0.8rem;
  font-weight: 400;
  color: #666;
  margin-top: 4px;
}

.menu-btn.secondary {
  border-color: var(--border-color);
  color: #444;
}

.field-select {
  background: var(--card-bg);
  padding: 14px;
  border-radius: 12px;
  margin-bottom: 12px;
  border: 1px solid var(--border-color);
}

.field-select h3 {
  margin-bottom: 10px;
  font-size: 0.95rem;
  color: #555;
}

/* ---- Question card ---- */

.q-header-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 10px;
}

.q-home-btn {
  width: auto;
  padding: 7px 14px;
  font-size: 0.88rem;
  margin-bottom: 0;
}

.exam-progress-text {
  font-size: 0.9rem;
  font-weight: 600;
  color: #555;
}

.question-card {
  background: var(--card-bg);
  border-radius: 12px;
  padding: 16px;
  margin-bottom: 12px;
  box-shadow: 0 1px 4px rgba(0,0,0,0.08);
}

.question-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 12px;
}

.tag {
  background: var(--exp-bg);
  padding: 3px 9px;
  border-radius: 20px;
  font-size: 0.78rem;
  color: #555;
  font-weight: 500;
}

.tag-correct {
  background: var(--correct-bg);
  color: var(--correct-color);
  font-weight: 700;
}

.tag-wrong {
  background: var(--wrong-bg);
  color: var(--wrong-color);
  font-weight: 700;
}

.question-text {
  font-size: 1rem;
  white-space: pre-wrap;
  line-height: 1.7;
}

#q-image-container {
  margin-top: 12px;
  text-align: center;
}

#q-image {
  max-width: 100%;
  width: 390px;
  height: auto;
  border: 1px solid var(--border-color);
  border-radius: 6px;
}

/* ---- Choices ---- */

.choices-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 12px;
}

.choice-item {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.choice-btn {
  background: var(--card-bg);
  border: 1.5px solid var(--border-color);
  padding: 14px 16px;
  border-radius: 10px;
  font-size: 0.98rem;
  text-align: left;
  cursor: pointer;
  display: flex;
  align-items: flex-start;
  gap: 12px;
  transition: border-color 0.15s, background 0.15s;
  width: 100%;
}

.choice-btn:active:not(:disabled) {
  background: #e8f0fb;
}

.choice-btn:disabled {
  cursor: default;
  opacity: 1;
}

.choice-btn.choice-correct {
  background: var(--correct-bg);
  border-color: var(--correct-border);
  border-width: 2px;
}

.choice-btn.choice-wrong {
  background: var(--wrong-bg);
  border-color: var(--wrong-border);
  border-width: 2px;
}

.choice-label {
  font-weight: 700;
  color: var(--primary-color);
  font-size: 1.05rem;
  flex-shrink: 0;
  min-width: 20px;
}

.choice-btn.choice-correct .choice-label { color: var(--correct-color); }
.choice-btn.choice-wrong .choice-label { color: var(--wrong-color); }

.choice-text {
  flex: 1;
  white-space: pre-wrap;
}

/* ---- Inline explanation ---- */

.choice-exp {
  font-size: 0.88rem;
  line-height: 1.6;
  padding: 10px 14px;
  border-radius: 0 0 8px 8px;
  border: 1.5px solid var(--border-color);
  border-top: none;
  background: var(--exp-bg);
  margin-top: -2px;
  white-space: pre-wrap;
}

.choice-exp.exp-correct {
  background: var(--correct-bg);
  border-color: var(--correct-border);
  color: #1b5e20;
}

.choice-exp.exp-wrong {
  background: var(--wrong-bg);
  border-color: var(--wrong-border);
  color: #7f0000;
}

/* ---- Overall explanation ---- */

.overall-explanation {
  margin: 8px 0 12px;
}

.overall-explanation-inner {
  background: var(--exp-bg);
  border-left: 4px solid var(--primary-color);
  border-radius: 0 8px 8px 0;
  padding: 12px 14px;
  font-size: 0.92rem;
  line-height: 1.7;
}

.overall-explanation-inner strong {
  display: block;
  margin-bottom: 6px;
  color: var(--primary-color);
}

/* ---- Post-answer navigation ---- */

.post-answer-nav {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-top: 4px;
  margin-bottom: 16px;
}

/* ---- Buttons ---- */

.primary-btn {
  background: var(--primary-color);
  color: white;
  border: none;
  padding: 15px;
  width: 100%;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: background 0.15s;
}

.primary-btn:active { background: #005099; }

.secondary-btn {
  background: var(--exp-bg);
  border: 1px solid var(--border-color);
  padding: 12px;
  width: 100%;
  border-radius: 10px;
  font-size: 0.95rem;
  cursor: pointer;
  color: #333;
  transition: background 0.15s;
}

.secondary-btn:active { background: #e2e2e8; }

/* ---- Stats screen ---- */

.stat-card {
  background: var(--card-bg);
  padding: 18px;
  border-radius: 12px;
  margin-bottom: 12px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.08);
}

.stat-card h3 {
  font-size: 0.95rem;
  color: #555;
  margin-bottom: 8px;
}

.data-management { margin-top: 24px; }

/* ---- Recent history ---- */

.recent-history-box {
  background: var(--card-bg);
  padding: 14px;
  border-radius: 12px;
  margin-top: 16px;
  border: 1px solid var(--border-color);
}

.recent-history-box h3 {
  margin-bottom: 10px;
  font-size: 0.95rem;
  color: #555;
}

.recent-item {
  padding: 8px 0;
  border-bottom: 1px solid var(--exp-bg);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.9rem;
}

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

.review-btn {
  background: var(--primary-color);
  color: white;
  border: none;
  padding: 4px 12px;
  border-radius: 6px;
  font-size: 0.82rem;
  cursor: pointer;
}

/* ---- Screen animation ---- */

.screen { animation: fadeIn 0.2s ease; }

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ---- Mistakes menu button ---- */

.menu-btn-mistakes {
  border-color: #c62828;
  color: #c62828;
}

.menu-btn-mistakes:active { background: #fff3f3; }

/* ---- Mistakes screen ---- */

.mistakes-top {
  background: var(--card-bg);
  border-radius: 12px;
  padding: 14px 16px;
  margin-bottom: 12px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.08);
  text-align: center;
}

.mistakes-summary {
  font-size: 1rem;
  font-weight: 700;
  color: #333;
  margin-bottom: 10px;
}

.mistakes-drill-btn {
  background: #c62828;
}

.mistakes-drill-btn:active { background: #8e1616; }

/* ---- Filter bar ---- */

.filter-bar {
  background: var(--card-bg);
  border-radius: 10px;
  padding: 10px 12px;
  margin-bottom: 12px;
  border: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.filter-row {
  display: flex;
  align-items: center;
  gap: 6px;
}

.filter-label {
  font-size: 0.78rem;
  color: #888;
  white-space: nowrap;
  min-width: 32px;
}

.filter-group {
  display: flex;
  gap: 4px;
  flex-wrap: wrap;
}

.filter-btn {
  padding: 4px 10px;
  border: 1.5px solid var(--border-color);
  background: var(--bg-color);
  border-radius: 20px;
  font-size: 0.8rem;
  cursor: pointer;
  color: #555;
  transition: all 0.15s;
}

.filter-btn.active {
  background: var(--primary-color);
  border-color: var(--primary-color);
  color: white;
  font-weight: 600;
}

/* ---- Mistake rows ---- */

.mistake-row {
  background: var(--card-bg);
  border-radius: 10px;
  padding: 12px 14px;
  margin-bottom: 8px;
  box-shadow: 0 1px 2px rgba(0,0,0,0.06);
  cursor: pointer;
  border: 1px solid var(--border-color);
  transition: background 0.15s;
}

.mistake-row:active { background: #f0f0f5; }

.mistake-row-main {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 5px;
}

.mistake-row-left {
  display: flex;
  align-items: center;
  gap: 6px;
}

.mistake-qid {
  font-weight: 700;
  font-size: 0.95rem;
}

.mistake-field-tag {
  font-size: 0.75rem;
  color: #888;
  background: var(--exp-bg);
  padding: 2px 7px;
  border-radius: 10px;
}

.mistake-row-snippet {
  font-size: 0.82rem;
  color: #666;
  margin-bottom: 5px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.mistake-row-sub {
  display: flex;
  gap: 14px;
  font-size: 0.8rem;
  color: #888;
}

.badge {
  padding: 3px 10px;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 700;
  white-space: nowrap;
}

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

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

.mistakes-empty {
  text-align: center;
  color: #aaa;
  padding: 40px 16px;
  font-size: 0.95rem;
}

/* ---- Action sheet ---- */

.action-sheet-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0,0,0,0.45);
  z-index: 1000;
  display: flex;
  align-items: flex-end;
  justify-content: center;
}

.action-sheet {
  background: var(--card-bg);
  border-radius: 16px 16px 0 0;
  padding: 16px 16px 32px;
  width: 100%;
  max-width: 600px;
}

.action-sheet-title {
  text-align: center;
  font-size: 0.85rem;
  color: #888;
  margin-bottom: 14px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
  line-height: 1.5;
}

.action-btn {
  display: block;
  width: 100%;
  padding: 14px;
  border: none;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  margin-bottom: 8px;
  background: var(--exp-bg);
  color: #333;
  text-align: center;
  transition: background 0.15s;
}

.action-btn:active { background: #e0e0ea; }

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

.action-btn-primary:active { background: #005099; }

.action-btn-cancel {
  background: transparent;
  color: #aaa;
  font-weight: 400;
  margin-top: 2px;
  margin-bottom: 0;
}

/* ---- Dictionary screen ---- */

.dict-top {
  background: var(--card-bg);
  border-radius: 12px;
  padding: 12px 14px;
  margin-bottom: 10px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.08);
}

.dict-count-text {
  font-size: 0.82rem;
  color: #888;
  margin-bottom: 8px;
}

.dict-search {
  width: 100%;
  padding: 9px 12px;
  border: 1.5px solid var(--border-color);
  border-radius: 8px;
  font-size: 0.95rem;
  background: var(--bg-color);
  color: var(--text-color);
  outline: none;
}

.dict-search:focus { border-color: var(--primary-color); }

.dict-az {
  display: flex;
  flex-wrap: wrap;
  gap: 3px;
  margin-bottom: 10px;
  background: var(--card-bg);
  padding: 8px 10px;
  border-radius: 10px;
  border: 1px solid var(--border-color);
}

.dict-az-btn {
  min-width: 26px;
  height: 26px;
  padding: 0 4px;
  border: 1.5px solid var(--border-color);
  background: var(--bg-color);
  border-radius: 5px;
  font-size: 0.78rem;
  font-weight: 600;
  cursor: pointer;
  color: #555;
  transition: all 0.12s;
  text-align: center;
}

.dict-az-btn.active {
  background: var(--primary-color);
  border-color: var(--primary-color);
  color: white;
}

.dict-az-btn.empty {
  opacity: 0.3;
  cursor: default;
}

.dict-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.dict-section-header {
  font-size: 0.8rem;
  color: #aaa;
  padding: 8px 4px 2px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.dict-term-row {
  background: var(--card-bg);
  border-radius: 10px;
  border: 1px solid var(--border-color);
  overflow: hidden;
  transition: border-color 0.15s;
}

.dict-term-row.open { border-color: var(--primary-color); }

.dict-term-header {
  padding: 11px 14px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  position: relative;
}

.dict-term-header:active { background: var(--exp-bg); }

.dict-term-main {
  display: flex;
  align-items: center;
  gap: 6px;
  flex: 1;
}

.dict-term-name {
  font-size: 1rem;
  font-weight: 700;
  color: var(--primary-color);
}

.dict-q-count {
  font-size: 0.78rem;
  background: var(--exp-bg);
  color: #666;
  padding: 2px 7px;
  border-radius: 10px;
  white-space: nowrap;
  flex-shrink: 0;
}

.badge-unconfirmed {
  background: #fff3e0;
  color: #e65100;
  border: 1px solid #ffcc80;
  padding: 1px 6px;
  border-radius: 10px;
  font-size: 0.72rem;
  font-weight: 700;
}

.dict-term-detail {
  border-top: 1px solid var(--border-color);
  padding: 12px 14px;
  background: var(--exp-bg);
}

.dict-detail-full {
  font-size: 0.88rem;
  color: #444;
  margin-bottom: 2px;
  font-weight: 600;
  word-break: break-word;
  white-space: normal;
}

.dict-detail-reading {
  font-size: 0.82rem;
  color: #666;
  margin-bottom: 8px;
  word-break: break-word;
  white-space: normal;
}

.dict-detail-meaning {
  font-size: 0.88rem;
  color: #333;
  margin-bottom: 8px;
  word-break: break-word;
  white-space: normal;
}

.dict-detail-qs-label {
  font-size: 0.78rem;
  color: #888;
  margin: 8px 0 6px;
  font-weight: 600;
}

.dict-detail-unconfirmed {
  font-size: 0.85rem;
  color: #e65100;
  margin-bottom: 8px;
}

.dict-q-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.dict-q-item {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 9px 11px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.dict-q-info {
  display: flex;
  align-items: center;
  gap: 6px;
  flex: 1;
  min-width: 0;
}

.dict-q-id {
  font-weight: 700;
  font-size: 0.85rem;
  white-space: nowrap;
}

.dict-q-field {
  font-size: 0.72rem;
  background: var(--exp-bg);
  color: #888;
  padding: 1px 5px;
  border-radius: 8px;
  white-space: nowrap;
}

.dict-q-snippet {
  font-size: 0.78rem;
  color: #888;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.dict-q-actions {
  display: flex;
  gap: 4px;
  flex-shrink: 0;
}

.dict-q-btn {
  padding: 4px 9px;
  border: 1.5px solid var(--border-color);
  background: var(--card-bg);
  border-radius: 6px;
  font-size: 0.78rem;
  cursor: pointer;
  color: #444;
  white-space: nowrap;
}

.dict-q-btn-redo {
  background: var(--primary-color);
  border-color: var(--primary-color);
  color: white;
}

.dict-empty {
  text-align: center;
  color: #aaa;
  padding: 40px 16px;
  font-size: 0.95rem;
}

/* ---- Skip button ---- */

.skip-btn-wrap {
  margin-bottom: 10px;
}

.skip-btn {
  display: block;
  width: 100%;
  padding: 13px;
  border: 2px dashed #aaa;
  background: transparent;
  border-radius: 10px;
  font-size: 0.95rem;
  color: #888;
  cursor: pointer;
  transition: all 0.15s;
  text-align: center;
}

.skip-btn:active {
  background: var(--exp-bg);
  color: #555;
  border-color: #888;
}

.skip-indicator {
  text-align: center;
  font-size: 0.85rem;
  color: #888;
  padding: 8px;
  background: var(--exp-bg);
  border-radius: 8px;
  margin-bottom: 8px;
}

/* ---- Skip badge in mistake rows ---- */

.badge-skip {
  background: #fff8e1;
  color: #f57f17;
  border: 1px solid #ffe082;
  padding: 3px 9px;
  border-radius: 20px;
  font-size: 0.72rem;
  font-weight: 600;
  white-space: nowrap;
}

/* ---- Tag for skip in exam review ---- */

.tag-skip {
  background: #fff8e1;
  color: #f57f17;
  font-weight: 700;
}