:root {
  --bg: #f4efe4;
  --paper: #fffdf8;
  --ink: #2f332e;
  --muted: #6f746c;
  --line: #d9d1c2;
  --accent: #486c59;
  --accent-dark: #335141;
  --soft: #e7eee8;
  --warm: #f1e5ca;
  --danger: #8a4f4a;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Kaku Gothic ProN", "Yu Gothic", sans-serif;
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--ink); font-size: 18px; line-height: 1.75; }
button { font: inherit; }
button:focus-visible, summary:focus-visible { outline: 3px solid #9ab8a5; outline-offset: 3px; }
.app-header { max-width: 760px; margin: 0 auto; padding: 22px 18px 10px; display: flex; align-items: center; justify-content: space-between; }
.app-header h1 { margin: 0; font-size: 1.45rem; letter-spacing: .04em; }
.eyebrow, .kicker { margin: 0 0 2px; color: var(--accent); font-size: .78rem; font-weight: 700; letter-spacing: .12em; }
.container { max-width: 760px; margin: 0 auto; padding: 10px 16px 36px; }
.view { display: none; }
.view.active { display: block; }
.hero-card, .panel, .question-card, .timeline-card, .weak-card { background: var(--paper); border: 1px solid var(--line); border-radius: 22px; box-shadow: 0 8px 24px rgba(65,58,43,.06); }
.hero-card { padding: 28px 22px; }
.hero-card h2 { font-size: 2rem; margin: 4px 0 8px; }
.hero-card p { margin-top: 0; }
.stats-row { display: grid; grid-template-columns: repeat(3,1fr); gap: 8px; margin: 22px 0; }
.stats-row div { text-align: center; padding: 12px 6px; background: #f8f5ee; border-radius: 14px; }
.stats-row strong { display: block; font-size: 1.5rem; }
.stats-row span { display: block; color: var(--muted); font-size: .75rem; }
.primary, .secondary, .ghost, .danger, .rating { border: 0; border-radius: 14px; cursor: pointer; min-height: 48px; }
.primary { background: var(--accent); color: white; padding: 12px 18px; font-weight: 700; }
.primary:hover { background: var(--accent-dark); }
.big { width: 100%; min-height: 58px; }
.secondary { background: var(--paper); color: var(--ink); border: 1px solid var(--line); padding: 10px 14px; }
.ghost { background: transparent; color: var(--accent-dark); padding: 8px 12px; }
.small { min-height: 40px; font-size: .9rem; }
.danger { background: #f5e8e6; color: var(--danger); padding: 10px 14px; }
.panel { margin-top: 18px; padding: 20px; }
.section-head { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; }
.section-head h2 { margin: 0; font-size: 1.25rem; }
.section-head span { color: var(--muted); font-size: .78rem; }
.big-head { align-items: center; margin-bottom: 16px; }
.big-head h2 { font-size: 1.8rem; }
.chapter-list { display: grid; gap: 10px; margin-top: 14px; }
.chapter { padding: 13px 14px; border-radius: 14px; background: #f8f5ee; border-left: 5px solid var(--accent); }
.chapter strong { display: block; }
.chapter span { color: var(--muted); font-size: .85rem; }
.home-actions { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin-top: 18px; }
.settings summary { cursor: pointer; font-weight: 700; }
.settings p { color: var(--muted); font-size: .9rem; }
.study-topline { display: flex; justify-content: space-between; color: var(--muted); font-size: .88rem; margin: 8px 6px 10px; }
.question-card { padding: 26px 22px; }
.question-label { color: var(--accent); font-size: .82rem; font-weight: 700; letter-spacing: .08em; }
.question-card h2 { min-height: 96px; display: flex; align-items: center; margin: 8px 0 12px; font-size: 1.55rem; line-height: 1.5; }
.hint { color: var(--muted); font-size: .88rem; }
.answer-area { border-top: 1px solid var(--line); margin-top: 22px; padding-top: 18px; }
.answer-main { font-size: 1.55rem; font-weight: 800; margin: 0; }
.answer-reading { margin: 0; color: var(--accent-dark); font-weight: 700; }
.answer-meta { margin: 12px 0 4px; font-size: .9rem; }
.answer-summary { margin-top: 6px; }
.rating-grid { display: grid; grid-template-columns: repeat(3,1fr); gap: 8px; margin-top: 22px; }
.rating { padding: 10px 6px; color: var(--ink); }
.rating strong, .rating span { display: block; }
.rating span { font-size: .7rem; margin-top: 3px; }
.rating.good { background: #dfeadf; }
.rating.unsure { background: #f3e8c9; }
.rating.again { background: #f2deda; }
#quitStudyBtn { width: 100%; margin-top: 12px; }
.timeline-note { background: var(--warm); border-radius: 14px; padding: 12px 14px; font-size: .88rem; margin-bottom: 16px; }
.timeline { display: grid; gap: 14px; }
.timeline-card { padding: 18px; position: relative; overflow: hidden; }
.timeline-card::before { content: ""; position: absolute; left: 0; top: 0; bottom: 0; width: 5px; background: var(--accent); }
.timeline-year { color: var(--accent); font-weight: 800; }
.timeline-title { margin: 2px 0 0; font-size: 1.18rem; }
.timeline-reading { margin: 0; color: var(--muted); font-size: .88rem; }
.timeline-people { font-size: .84rem; color: var(--accent-dark); }
.timeline-summary { margin-bottom: 0; }
.weak-list { display: grid; gap: 10px; margin-bottom: 18px; }
.weak-card { padding: 14px 16px; }
.weak-card strong { display: block; }
.weak-card span { color: var(--muted); font-size: .84rem; }
.empty { text-align: center; background: var(--paper); border-radius: 18px; padding: 28px 20px; border: 1px solid var(--line); }
footer { max-width: 760px; margin: 0 auto; padding: 12px 18px 34px; color: var(--muted); text-align: center; font-size: .8rem; }
@media (max-width: 520px) {
  body { font-size: 17px; }
  .container { padding-left: 12px; padding-right: 12px; }
  .hero-card, .question-card { border-radius: 18px; }
  .rating-grid { grid-template-columns: 1fr; }
  .rating { text-align: left; padding-left: 16px; }
  .home-actions { grid-template-columns: 1fr; }
}