:root {
  --bg: #f5f6fa;
  --card: #ffffff;
  --border: #d8dde6;
  --text: #1f2329;
  --muted: #6b7280;
  --primary: #2563eb;
  --primary-dark: #1e40af;
  --primary-soft: #eef3ff;
  --correct: #16a34a;
  --correct-bg: #dcfce7;
  --incorrect: #dc2626;
  --incorrect-bg: #fee2e2;
  --warn: #d97706;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", "Noto Sans JP", "Yu Gothic UI", sans-serif;
  font-size: 16px;
  line-height: 1.6;
}

header {
  background: var(--primary);
  color: #fff;
  padding: 12px 20px;
  position: sticky;
  top: 0;
  z-index: 10;
  box-shadow: 0 2px 4px rgba(0,0,0,0.08);
  display: flex;
  align-items: center;
  gap: 12px;
}

header .link-button {
  background: none;
  border: none;
  color: #fff;
  font-size: 18px;
  font-weight: bold;
  cursor: pointer;
  padding: 0;
  font-family: inherit;
}

header .header-action {
  margin-left: auto;
  background: rgba(255, 255, 255, 0.15);
  border: 1px solid rgba(255, 255, 255, 0.3);
  color: #fff;
  font-size: 13px;
  cursor: pointer;
  padding: 5px 12px;
  border-radius: 4px;
  font-family: inherit;
  white-space: nowrap;
}
header .header-action:hover { background: rgba(255, 255, 255, 0.25); }
header .header-action:disabled { opacity: 0.6; cursor: wait; }
header .header-action.reloading::before { content: ""; }

main {
  max-width: 880px;
  margin: 0 auto;
  padding: 24px 16px 80px;
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 20px;
  margin-bottom: 16px;
}

h2 { margin-top: 0; font-size: 1.4em; }
h3 { font-size: 1.1em; margin-top: 0; }

code { background: #f1f5f9; padding: 2px 4px; border-radius: 3px; font-size: 0.9em; }

.btn {
  display: inline-block;
  padding: 10px 20px;
  border-radius: 6px;
  border: 1px solid var(--primary);
  background: var(--primary);
  color: #fff;
  font-size: 15px;
  cursor: pointer;
  font-family: inherit;
}
.btn:hover:not(:disabled) { background: var(--primary-dark); }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }

.btn-secondary {
  background: #fff;
  color: var(--primary);
}
.btn-secondary:hover:not(:disabled) { background: var(--primary-soft); }

.btn-warn {
  background: var(--warn);
  border-color: var(--warn);
}
.btn-warn:hover:not(:disabled) { background: #b45309; }

.mode-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
  margin-top: 12px;
}
@media (min-width: 640px) {
  .mode-grid { grid-template-columns: repeat(3, 1fr); }
}

.mode-card {
  display: block;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 18px;
  cursor: pointer;
  text-align: left;
  font-family: inherit;
  font-size: 15px;
  color: inherit;
  transition: border-color 0.15s, box-shadow 0.15s;
}
.mode-card:hover { border-color: var(--primary); box-shadow: 0 2px 8px rgba(0,0,0,0.08); }
.mode-card .mode-title { font-weight: bold; font-size: 1.05em; margin-bottom: 6px; color: var(--primary); }
.mode-card .mode-desc { color: var(--muted); font-size: 0.9em; line-height: 1.5; }

.filter-row {
  display: grid;
  grid-template-columns: 110px 1fr;
  gap: 8px 12px;
  align-items: center;
  margin-bottom: 12px;
}

.filter-row label { font-weight: bold; }
.filter-row select,
.filter-row input[type="text"] {
  padding: 8px 10px;
  font-size: 15px;
  border-radius: 6px;
  border: 1px solid var(--border);
  font-family: inherit;
  width: 100%;
  background: #fff;
}
.filter-row select:focus,
.filter-row input:focus {
  outline: 2px solid var(--primary);
  outline-offset: -1px;
  border-color: var(--primary);
}

.stats { color: var(--muted); }
.stats strong { color: var(--text); }

.question-card { padding: 20px; margin-bottom: 16px; }
.q-header {
  color: var(--muted);
  font-size: 0.9em;
  margin-bottom: 8px;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 6px;
}
.q-text { white-space: pre-wrap; margin-bottom: 16px; font-size: 1.05em; line-height: 1.7; }

/* ----- データソース設定 ----- */
.qual-block {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px 14px;
  margin-bottom: 12px;
  background: #fafbfc;
}
.qual-header {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 8px;
  padding-bottom: 8px;
  border-bottom: 1px dashed var(--border);
}
.qual-name {
  font-weight: bold;
  font-size: 1.05em;
  color: var(--primary);
}
.qual-stats {
  color: var(--muted);
  font-size: 0.9em;
}
.qual-header .btn-link-warn {
  margin-left: auto;
}

.db-list { list-style: none; padding: 0; margin: 0 0 8px; }
.db-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 6px 0;
  font-size: 0.92em;
  flex-wrap: wrap;
}
.db-item.db-error { color: var(--incorrect); }
.db-url {
  flex: 1;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  color: var(--text);
  text-decoration: none;
}
.db-url:hover { text-decoration: underline; color: var(--primary); }
.db-error-msg {
  color: var(--incorrect);
  font-size: 0.9em;
  flex-basis: 100%;
}
.db-empty {
  color: var(--muted);
  font-style: italic;
  font-size: 0.9em;
  padding: 6px 0;
}

.add-row {
  display: flex;
  gap: 8px;
  align-items: center;
  flex-wrap: wrap;
}
.add-row input[type="text"] {
  flex: 1;
  min-width: 200px;
  padding: 7px 10px;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 14px;
  font-family: inherit;
}
.add-row input:focus { outline: 2px solid var(--primary); outline-offset: -1px; border-color: var(--primary); }

.add-qual-form {
  margin-top: 16px;
  padding: 12px;
  background: #f1f5f9;
  border-radius: 6px;
  border: 1px dashed var(--primary);
}
.add-qual-form h4 { margin: 0 0 8px; font-size: 1em; color: var(--primary); }

.btn-small { padding: 6px 12px; font-size: 13px; }

.btn-link-warn {
  background: none;
  border: none;
  color: var(--incorrect);
  font-size: 0.85em;
  cursor: pointer;
  padding: 2px 6px;
  font-family: inherit;
  border-radius: 4px;
}
.btn-link-warn:hover { background: var(--incorrect-bg); }

.info-banner {
  padding: 10px 12px;
  background: #fef3c7;
  color: #92400e;
  border-radius: 6px;
  margin-bottom: 12px;
  font-size: 0.92em;
}

/* ----- 問題内画像 ----- */
.q-images {
  margin: 0 0 16px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.q-image {
  display: block;
  max-width: 100%;
  height: auto;
  border: 1px solid var(--border);
  border-radius: 4px;
  background: #fff;
}

/* KaTeX 未読込時のフォールバック表示(オフライン+未キャッシュ等) */
.tex-fallback {
  background: #fef3c7;
  color: #92400e;
  padding: 1px 6px;
  border-radius: 3px;
  font-size: 0.92em;
  font-family: ui-monospace, "Consolas", monospace;
}

/* 選択肢内に表示する画像(ファイル名 *_ch{N}.png に対応) */
.choice-image {
  display: block;
  max-width: 100%;
  height: auto;
  margin-top: 6px;
  border: 1px solid var(--border);
  border-radius: 4px;
  background: #fff;
}

.choices { list-style: none; padding: 0; margin: 0; }
.choices li { margin-bottom: 8px; }

.choice {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: 6px;
  cursor: pointer;
  background: #fff;
}
.choice:not(.disabled):hover { background: var(--primary-soft); }
.choice.selected { border-color: var(--primary); background: var(--primary-soft); }
.choice.correct { border-color: var(--correct); background: var(--correct-bg); }
.choice.incorrect { border-color: var(--incorrect); background: var(--incorrect-bg); }
.choice.disabled { cursor: default; }

/* 中断セッションの再開カード */
.resume-card {
  border-left: 4px solid var(--warn);
  background: #fffbeb;
}
.resume-card h3 { color: var(--warn); margin-bottom: 8px; }
.resume-card .stats { color: var(--text); }
.resume-card .actions { margin-top: 12px; }

/* 学習履歴エクスポートカード(prompt-card と同じ見た目) */
.export-card {
  margin-bottom: 16px;
}
.export-card > summary {
  cursor: pointer;
  padding: 12px 14px;
  background: #f1f5f9;
  border-radius: 6px;
  font-weight: bold;
  list-style: none;
  user-select: none;
  margin: -20px -20px 0;
}
.export-card > summary::-webkit-details-marker { display: none; }
.export-card > summary::before {
  content: "▶";
  display: inline-block;
  margin-right: 8px;
  font-size: 0.8em;
  transition: transform 0.15s ease;
}
.export-card[open] > summary::before { transform: rotate(90deg); }
.export-card[open] > summary {
  margin-bottom: 16px;
  border-bottom: 1px solid var(--border);
}
.export-card > summary:hover { background: #e2e8f0; }

/* 問題作成プロンプトのコピー用カード */
.prompt-card {
  margin-bottom: 16px;
}
.prompt-card > summary {
  cursor: pointer;
  padding: 12px 14px;
  background: #f1f5f9;
  border-radius: 6px;
  font-weight: bold;
  list-style: none;
  user-select: none;
  margin: -20px -20px 0;  /* card padding を相殺してフルワイド表示 */
}
.prompt-card > summary::-webkit-details-marker { display: none; }
.prompt-card > summary::before {
  content: "▶";
  display: inline-block;
  margin-right: 8px;
  font-size: 0.8em;
  transition: transform 0.15s ease;
}
.prompt-card[open] > summary::before { transform: rotate(90deg); }
.prompt-card[open] > summary {
  margin-bottom: 16px;
  border-bottom: 1px solid var(--border);
}
.prompt-card > summary:hover { background: #e2e8f0; }

.prompt-actions {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 10px;
}
.prompt-status {
  font-size: 0.9em;
  font-weight: bold;
}
.prompt-card textarea {
  width: 100%;
  min-height: 280px;
  padding: 10px;
  font-family: ui-monospace, "Consolas", "Menlo", monospace;
  font-size: 0.85em;
  line-height: 1.5;
  border: 1px solid var(--border);
  border-radius: 6px;
  resize: vertical;
  white-space: pre;
  background: #fafbfc;
  color: var(--text);
}
.prompt-card textarea:focus { outline: 2px solid var(--primary); outline-offset: -1px; }

/* フィルタの複数選択チェックボックス(チップ風) */
.multi-check {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 8px;
}
.multi-check label {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 12px;
  border: 1px solid var(--border);
  border-radius: 16px;
  cursor: pointer;
  font-size: 0.92em;
  background: #fff;
  user-select: none;
  transition: background 0.1s, border-color 0.1s;
}
.multi-check label:hover { background: var(--primary-soft); }
.multi-check label:has(input:checked) {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}
.multi-check input[type="checkbox"] { margin: 0; cursor: pointer; }

.radio-group {
  display: flex;
  gap: 16px;
}
.radio-group label {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  cursor: pointer;
  user-select: none;
}
.radio-group input[type="radio"] { width: 16px; height: 16px; margin: 0; cursor: pointer; }

.filter-note {
  color: var(--muted);
  font-size: 0.85em;
  margin: -4px 0 12px 0;
  padding-left: 122px;
}
.muted { color: var(--muted); font-size: 0.9em; }

/* 選択肢内の左側ラジオボタン領域(クリックで選択) */
.choice-radio-wrap {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 4px 6px 4px 0;
  cursor: pointer;
  flex-shrink: 0;
}
.choice-radio-wrap input[type="radio"] {
  width: 18px;
  height: 18px;
  margin: 0;
  cursor: pointer;
}

/* 選択肢の本文領域(クリックで取り消し線トグル) */
.choice-body {
  flex: 1;
  display: flex;
  align-items: flex-start;
  gap: 8px;
  cursor: pointer;
  min-width: 0;
}
.choice.disabled .choice-body { cursor: default; }

/* 取り消し線(候補から外す) */
.choice.struck {
  background: #f3f4f6;
  border-color: #d1d5db;
}
.choice.struck .choice-text {
  text-decoration: line-through;
  text-decoration-thickness: 2px;
  opacity: 0.55;
}
.choice.struck .choice-num {
  opacity: 0.55;
}

.choice-num { font-weight: bold; color: var(--muted); min-width: 1.6em; flex-shrink: 0; }
.choice-text { flex: 1; }

.choice-explanation {
  margin-top: 8px;
  padding: 8px 10px;
  background: rgba(255,255,255,0.7);
  border-left: 3px solid var(--muted);
  font-size: 0.93em;
  white-space: pre-wrap;
  border-radius: 0 4px 4px 0;
}

.explanation-box {
  margin-top: 16px;
  margin-bottom: 16px;
  padding: 14px 16px;
  background: #f1f5f9;
  border-left: 4px solid var(--primary);
  border-radius: 4px;
  white-space: pre-wrap;
  line-height: 1.7;
}
.explanation-box .label { font-weight: bold; margin-bottom: 4px; color: var(--primary); }

/* ヒントは解答後にも表示する場合、解説と区別するため黄色アクセント */
.explanation-box.explanation-box-hint {
  background: #fffbeb;
  border-left-color: var(--warn);
}
.explanation-box.explanation-box-hint .label { color: var(--warn); }

/* 解説表示モードでの「全般解説を見る」開閉トグル */
.overall-toggle {
  margin: 0 0 16px;
}
.overall-toggle > summary {
  cursor: pointer;
  padding: 10px 14px;
  background: #eef3ff;
  border: 1px dashed var(--primary);
  border-radius: 6px;
  font-weight: bold;
  color: var(--primary);
  list-style: none;
  user-select: none;
  font-size: 0.95em;
}
.overall-toggle > summary::-webkit-details-marker { display: none; }
.overall-toggle > summary::before {
  content: "▶";
  display: inline-block;
  margin-right: 8px;
  font-size: 0.8em;
  transition: transform 0.15s ease;
}
.overall-toggle[open] > summary::before {
  transform: rotate(90deg);
}
.overall-toggle > summary:hover {
  background: #dde7ff;
}
.overall-toggle > .explanation-box {
  margin-top: 8px;
  margin-bottom: 0;
}

.result-judge {
  display: inline-block;
  padding: 2px 12px;
  border-radius: 12px;
  font-weight: bold;
  font-size: 0.85em;
}
.result-judge.correct { background: var(--correct-bg); color: var(--correct); }
.result-judge.incorrect { background: var(--incorrect-bg); color: var(--incorrect); }
.result-judge.unanswered { background: #f3f4f6; color: var(--muted); }

.actions {
  display: flex;
  gap: 10px;
  justify-content: flex-end;
  margin-top: 20px;
  flex-wrap: wrap;
}

/* 「要復習」チェックボックス行 */
.mark-review-row {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 14px;
  background: #fffbeb;
  border: 1px solid #fcd34d;
  border-radius: 6px;
  margin-top: 16px;
  cursor: pointer;
  font-size: 0.95em;
  color: #78350f;
  user-select: none;
}
.mark-review-row input[type="checkbox"] {
  width: 18px;
  height: 18px;
  cursor: pointer;
  margin: 0;
  accent-color: var(--warn);
}

.summary-banner {
  text-align: center;
  padding: 24px;
  background: linear-gradient(135deg, var(--primary-soft) 0%, #f1f5f9 100%);
  border-radius: 8px;
}
.summary-banner .score {
  font-size: 2.4em;
  font-weight: bold;
  color: var(--primary);
  line-height: 1.1;
  margin: 8px 0;
}
.summary-banner .label { color: var(--muted); }

.error {
  padding: 12px 14px;
  background: var(--incorrect-bg);
  color: var(--incorrect);
  border-radius: 6px;
  margin-bottom: 16px;
}

.progress {
  height: 6px;
  background: var(--border);
  border-radius: 3px;
  overflow: hidden;
  margin-bottom: 16px;
}
.progress-bar {
  height: 100%;
  background: var(--primary);
  transition: width 0.3s;
}