:root {
  --bg: #0f172a;
  --bg2: #1e293b;
  --card: #1e293b;
  --card2: #334155;
  --fg: #e2e8f0;
  --muted: #94a3b8;
  --accent: #38bdf8;
  --accent2: #0ea5e9;
  --good: #22c55e;
  --bad: #ef4444;
  --line: #334155;
}
* { box-sizing: border-box; -webkit-tap-highlight-color: transparent; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, "Segoe UI", "Hiragino Kaku Gothic ProN", "Yu Gothic", Meiryo, sans-serif;
  line-height: 1.6;
  padding-bottom: 150px;
}
.app-header {
  padding: 14px 16px calc(14px + env(safe-area-inset-top)) 16px;
  padding-top: calc(14px + env(safe-area-inset-top));
  background: linear-gradient(135deg, #0ea5e9, #6366f1);
}
.app-header h1 { margin: 0; font-size: 1.15rem; font-weight: 700; }
.app-header h1 span { display: block; font-size: .8rem; font-weight: 400; opacity: .85; }

.tabs { display: flex; position: sticky; top: 0; z-index: 20; background: var(--bg); border-bottom: 1px solid var(--line); }
.tab { flex: 1; padding: 14px; background: none; border: none; color: var(--muted); font-size: 1rem; font-weight: 600; border-bottom: 3px solid transparent; cursor: pointer; }
.tab.active { color: var(--accent); border-bottom-color: var(--accent); }

main { padding: 14px; max-width: 720px; margin: 0 auto; }
.tab-panel { display: none; }
.tab-panel.active { display: block; }

.hint { font-size: .85rem; color: var(--muted); background: var(--bg2); border-left: 3px solid var(--accent); padding: 10px 12px; border-radius: 6px; margin-bottom: 14px; }

.quick-row { margin-bottom: 16px; }
.quick-btn {
  display: block; width: 100%; padding: 15px; margin: 6px 0;
  background: var(--accent2); color: #06283d; border: none; border-radius: 12px;
  font-size: 1.05rem; font-weight: 700; cursor: pointer;
}
.quick-btn:active { transform: scale(.99); }
.ghost-btn { background: none; border: 1px solid var(--line); color: var(--muted); padding: 12px; border-radius: 10px; width: 100%; margin-top: 8px; font-size: .95rem; cursor: pointer; }

.quick-filter { font-size: .82rem; color: var(--muted); margin-top: 8px; display: flex; flex-wrap: wrap; gap: 10px 14px; align-items: center; }
.quick-filter label { display: inline-flex; align-items: center; gap: 4px; }

.section-head { font-size: .95rem; font-weight: 700; color: var(--accent); margin: 18px 2px 8px; padding-bottom: 6px; border-bottom: 1px solid var(--line); }
.section-head:first-child { margin-top: 0; }
.chapter { background: var(--card); border-radius: 14px; margin-bottom: 12px; overflow: hidden; }
.chapter-head { padding: 14px 16px; }
.chapter-head .c-title { font-size: 1.05rem; font-weight: 700; }
.chapter-head .c-sub { font-size: .8rem; color: var(--muted); }
.track-row { display: flex; gap: 8px; padding: 0 12px 12px; flex-wrap: wrap; }
.track-btn {
  flex: 1; min-width: 90px; padding: 11px 8px; border-radius: 10px; border: 1px solid var(--card2);
  background: var(--bg2); color: var(--fg); font-size: .9rem; font-weight: 600; cursor: pointer;
  display: flex; flex-direction: column; align-items: center; gap: 2px;
}
.track-btn .t-dur { font-size: .72rem; color: var(--muted); font-weight: 400; }
.track-btn.playing { background: var(--accent2); color: #06283d; border-color: var(--accent); }

/* Player */
.player {
  position: fixed; left: 0; right: 0; bottom: 0; z-index: 30;
  background: var(--bg2); border-top: 1px solid var(--line);
  padding: 8px 12px calc(8px + env(safe-area-inset-bottom));
}
.player.hidden { display: none; }
.player-info { display: flex; flex-direction: column; }
.p-title { font-size: .95rem; font-weight: 700; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.p-sub { font-size: .76rem; color: var(--muted); }
.p-seek { width: 100%; margin: 6px 0 2px; accent-color: var(--accent); }
.player-controls { display: flex; align-items: center; gap: 6px; }
.player-controls button { background: var(--card2); color: var(--fg); border: none; border-radius: 10px; padding: 8px 12px; font-size: 1.1rem; cursor: pointer; }
.p-play { background: var(--accent) !important; color: #06283d !important; font-weight: 700; min-width: 52px; }
.p-speed { display: flex; gap: 3px; margin-left: auto; }
.speed-btn { font-size: .78rem !important; padding: 7px 8px !important; }
.speed-btn.active { background: var(--accent) !important; color: #06283d !important; }
.p-time { font-size: .72rem; color: var(--muted); min-width: 84px; text-align: right; }

/* Quiz */
.field { margin: 14px 0; }
.field label { display: block; font-size: .85rem; color: var(--muted); margin-bottom: 6px; }
select { width: 100%; padding: 12px; border-radius: 10px; background: var(--card); color: var(--fg); border: 1px solid var(--line); font-size: 1rem; }
.seg { display: flex; gap: 6px; }
.seg-btn { flex: 1; padding: 12px; border-radius: 10px; border: 1px solid var(--line); background: var(--card); color: var(--muted); font-weight: 600; cursor: pointer; }
.seg-btn.active { background: var(--accent2); color: #06283d; border-color: var(--accent); }
.wrong-count { margin-top: 14px; font-size: .85rem; color: var(--muted); text-align: center; }

.quiz-progress { font-size: .85rem; color: var(--muted); margin-bottom: 10px; }
.q-chapter { font-size: .78rem; color: var(--accent); margin-bottom: 4px; }
.q-text { font-size: 1.15rem; font-weight: 700; margin-bottom: 16px; }
.q-choices { display: flex; flex-direction: column; gap: 10px; }
.choice {
  text-align: left; padding: 14px 16px; border-radius: 12px; border: 1px solid var(--line);
  background: var(--card); color: var(--fg); font-size: 1rem; cursor: pointer; line-height: 1.4;
}
.choice:disabled { cursor: default; }
.choice.correct { background: rgba(34,197,94,.18); border-color: var(--good); }
.choice.wrong { background: rgba(239,68,68,.18); border-color: var(--bad); }
.q-explain { margin-top: 16px; padding: 14px; border-radius: 12px; background: var(--bg2); border-left: 3px solid var(--accent); font-size: .92rem; }
.quiz-actions { margin-top: 18px; }
.result-text { font-size: 1.1rem; text-align: center; margin: 24px 0; }

/* 間違い確認 */
.ghost-sm { width: auto; padding: 7px 12px; margin: 0; font-size: .8rem; }
.review-head { display: flex; align-items: center; justify-content: space-between; gap: 10px; margin-bottom: 12px; }
.review-head h2 { margin: 0; font-size: 1.15rem; }
.review-item { background: var(--card); border-radius: 12px; padding: 14px; margin-bottom: 12px; border-left: 3px solid var(--bad); }
.review-item .r-chapter { font-size: .76rem; color: var(--accent); margin-bottom: 4px; }
.review-item .r-q { font-weight: 700; margin-bottom: 8px; }
.review-item .r-ans { color: var(--good); font-weight: 600; margin-bottom: 8px; }
.review-item .r-explain { font-size: .9rem; color: var(--fg); background: var(--bg2); border-radius: 8px; padding: 10px 12px; white-space: pre-line; line-height: 1.6; }
.review-item .r-del { margin-top: 10px; background: none; border: 1px solid var(--line); color: var(--muted); padding: 6px 12px; border-radius: 8px; font-size: .78rem; cursor: pointer; }

.hidden { display: none !important; }