* { box-sizing: border-box; }
[hidden] { display: none !important; }
button, select, input { font: inherit; }
button { cursor: pointer; }
button:disabled, select:disabled { opacity: .45; cursor: not-allowed; }
.exercise-nav { display: flex; justify-content: space-between; align-items: center; gap: 16px; margin-bottom: 22px; font-size: 13px; }
.exercise-nav a { color: var(--accent-dark); }
.level { cursor: pointer; font: inherit; }
.book-ear .levels.three-levels { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.setting-pair { display: flex; align-items: center; flex-wrap: wrap; gap: 10px; }
.challenge-settings { display: flex; flex-wrap: wrap; align-items: center; gap: 14px; border-top: 1px solid var(--accent-line); margin-top: 18px; padding-top: 18px; }
.challenge-label { display: inline-flex; align-items: center; gap: 9px; font-weight: 800; min-height: 44px; }
.challenge-label input { width: 20px; height: 20px; accent-color: var(--accent-dark); }
.challenge-help { font-size: 14px; color: var(--muted); margin: 8px 0 0; }
.reference { margin-top: 18px; }
.reference p { margin: 0 0 12px; color: var(--muted); }
.timer-panel { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 10px; margin: 18px 0 0; padding: 14px 18px; background: var(--accent-wash); border: 1px solid var(--accent-line); }
.clock { font-size: 28px; font-weight: 800; font-variant-numeric: tabular-nums; }
.clock.urgent { color: var(--wrong); }
.timer-caption { font-size: 13px; color: var(--muted); }
.note-guide { margin-top: 18px; display: flex; align-items: center; gap: 10px; }
.note-dot { display: grid; place-items: center; height: 36px; width: 36px; border-radius: 50%; border: 1px solid var(--line-strong); background: #fff; font-size: 13px; font-weight: 800; color: var(--muted); }
.note-dot.target { border: 2px solid var(--accent); color: var(--accent-dark); background: var(--accent-wash); }
.note-dot.sounding { color: #fff; background: var(--accent-dark); border-color: var(--accent-dark); }
.target-text { color: var(--muted); font-size: 14px; margin: 10px 0 0; }
.answer-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin-top: 18px; }
.feedback { min-height: 30px; margin-top: 16px; font-weight: 700; }
.score { margin-top: 5px; }
.audio-status { min-height: 20px; font-size: 13px; color: var(--muted); margin: 10px 0 0; }
.summary { margin-top: 20px; padding: 20px 22px; background: var(--accent-wash); border-left: 4px solid var(--accent); }
.summary h2 { margin: 0 0 8px; font-size: 22px; }
.summary p { margin: 6px 0; }
.summary .result { font-size: 24px; font-weight: 800; }
.tip-area { margin-top: 20px; }
.overview-card { display: block; margin-top: 24px; padding: 22px; border: 1px solid var(--accent-line); color: var(--ink); text-decoration: none; background: #fff; }
.overview-card h2 { margin: 0 0 10px; font-size: 23px; }
.overview-card p { margin: 0 0 12px; color: var(--muted); }
.overview-card span { color: var(--accent-dark); font-weight: 800; }
.overview-card:hover { border-color: var(--accent); background: var(--accent-wash); }
@media (max-width: 680px) { .book-ear .levels.three-levels { grid-template-columns: 1fr; } }
@media (max-width: 450px) { .answer-grid { grid-template-columns: 1fr; } .exercise-nav { margin-bottom: 16px; } .timer-panel { padding: 12px 16px; } }