:root {
  --ink: #17202a;
  --muted: #5d6b78;
  --navy: #17324d;
  --blue: #2f5d7c;
  --blue-soft: #e9f1f7;
  --gold: #d9a441;
  --paper: #ffffff;
  --canvas: #f5f7fa;
  --line: #d9e1e8;
  --good: #176b3a;
  --good-soft: #e6f5ec;
  --bad: #a22828;
  --bad-soft: #fdecec;
  --shadow: 0 12px 34px rgba(23, 50, 77, 0.10);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--ink);
  background: var(--canvas);
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--canvas); color: var(--ink); line-height: 1.55; }
a { color: var(--blue); }
button, input, select { font: inherit; }
button { cursor: pointer; }
.learn-shell { width: min(1120px, calc(100% - 2rem)); margin-inline: auto; }
.learn-site-header { background: var(--navy); color: white; }
.learn-header-inner { min-height: 64px; display: flex; align-items: center; justify-content: space-between; gap: 1.5rem; }
.learn-brand { color: white; text-decoration: none; font-weight: 800; letter-spacing: .02em; }
.learn-site-header nav { display: flex; flex-wrap: wrap; gap: .4rem; }
.learn-site-header nav a { color: #dfeaf2; text-decoration: none; padding: .55rem .8rem; border-radius: 999px; }
.learn-site-header nav a:hover, .learn-site-header nav a[aria-current="page"] { background: rgba(255,255,255,.14); color: white; }
.learn-hero { padding: 4rem 0 2rem; }
.compact-hero { padding-bottom: 1.25rem; }
.learn-eyebrow { margin: 0 0 .35rem; color: var(--blue); font-weight: 800; text-transform: uppercase; letter-spacing: .09em; font-size: .78rem; }
h1 { margin: 0; font-size: clamp(2rem, 5vw, 3.8rem); line-height: 1.05; letter-spacing: -.035em; color: var(--navy); }
.learn-lead { max-width: 780px; color: var(--muted); font-size: 1.1rem; margin: 1rem 0 0; }
.learn-actions { display: flex; flex-wrap: wrap; gap: .75rem; margin-top: 1.4rem; }
.panel { background: var(--paper); border: 1px solid var(--line); border-radius: 18px; box-shadow: var(--shadow); padding: clamp(1rem, 3vw, 1.6rem); margin: 0 0 1.5rem; }
.controls-panel { position: sticky; top: .75rem; z-index: 10; }
.control-grid { display: grid; grid-template-columns: minmax(220px, 2fr) repeat(3, minmax(150px, 1fr)); gap: .9rem; align-items: end; }
.quiz-control-grid { grid-template-columns: repeat(3, minmax(150px, 1fr)) repeat(2, minmax(190px, 1fr)); }
.control { display: grid; gap: .35rem; color: var(--muted); font-size: .88rem; font-weight: 700; }
.control input, .control select { width: 100%; min-height: 44px; border: 1px solid #b8c5cf; border-radius: 10px; background: white; color: var(--ink); padding: .65rem .75rem; }
.control input:focus, .control select:focus, button:focus-visible, a:focus-visible { outline: 3px solid rgba(47, 93, 124, .28); outline-offset: 2px; }
.check-control { display: flex; gap: .6rem; align-items: center; min-height: 44px; font-weight: 650; color: var(--ink); }
.check-control input { width: 1.15rem; height: 1.15rem; accent-color: var(--blue); }
.results-toolbar { display: flex; justify-content: space-between; gap: 1rem; align-items: center; margin-top: 1rem; padding-top: 1rem; border-top: 1px solid var(--line); }
.results-toolbar p { margin: 0; color: var(--muted); }
.button { display: inline-flex; align-items: center; justify-content: center; min-height: 44px; padding: .7rem 1rem; border-radius: 10px; border: 1px solid transparent; text-decoration: none; font-weight: 800; }
.button-primary { background: var(--blue); color: white; }
.button-primary:hover { background: var(--navy); }
.button-secondary { background: white; color: var(--blue); border-color: #aebdca; }
.button-secondary:hover { background: var(--blue-soft); }
.vocab-list { list-style: none; padding: 0; margin: 0 0 3rem; display: grid; gap: .75rem; }
.vocab-card { display: grid; grid-template-columns: 64px minmax(140px, .9fr) minmax(220px, 1.6fr); gap: 1rem; align-items: start; background: white; border: 1px solid var(--line); border-radius: 15px; padding: 1rem 1.1rem; box-shadow: 0 5px 18px rgba(23,50,77,.05); }
.vocab-rank { display: inline-flex; align-items: center; justify-content: center; min-width: 48px; min-height: 34px; border-radius: 999px; background: var(--blue-soft); color: var(--navy); font-weight: 850; }
.vocab-term { font-size: 1.35rem; font-weight: 850; color: var(--navy); line-height: 1.2; }
.vocab-gloss { font-size: 1.04rem; }
.vocab-meta { grid-column: 2 / -1; display: flex; flex-wrap: wrap; align-items: center; gap: .45rem; }
.badge { display: inline-flex; align-items: center; border-radius: 999px; padding: .22rem .55rem; background: var(--canvas); border: 1px solid var(--line); color: var(--muted); font-size: .76rem; font-weight: 750; }
.badge-note { background: var(--bad-soft); color: #7c2727; border-color: #efcaca; }
.vocab-details { grid-column: 2 / -1; color: var(--muted); }
.vocab-details summary { color: var(--blue); font-weight: 750; cursor: pointer; }
.vocab-details p { margin: .55rem 0 0; }
.rank-evidence { display: flex; flex-wrap: wrap; gap: 1rem; font-size: .88rem; }
.empty-state { padding: 3rem 1rem; text-align: center; color: var(--muted); }
.quiz-settings h2 { margin-top: 0; color: var(--navy); }
.helper-text { color: var(--muted); font-size: .9rem; }
.quiz-stage { max-width: 860px; margin-inline: auto; }
.quiz-status { display: flex; justify-content: space-between; flex-wrap: wrap; gap: .75rem; color: var(--muted); font-weight: 750; font-size: .9rem; }
.progress-track { height: 8px; background: #e7edf2; border-radius: 999px; overflow: hidden; margin: .8rem 0 1.5rem; }
.progress-track span { display: block; width: 0; height: 100%; background: var(--gold); transition: width .25s ease; }
.statement-card { border: 1px solid var(--line); background: linear-gradient(145deg, #fff, #f7fafc); border-radius: 16px; padding: clamp(1.25rem, 4vw, 2.4rem); text-align: center; }
.statement-label { color: var(--muted); margin: 0 0 .8rem; font-weight: 700; }
.quiz-statement { margin: 0; color: var(--ink); font-size: clamp(1.45rem, 4vw, 2.35rem); line-height: 1.3; }
#quiz-term { color: var(--navy); }
.statement-equals { color: var(--muted); font-weight: 600; margin-inline: .3rem; }
#quiz-meaning { color: var(--blue); }
.answer-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin: 1.2rem 0; }
.answer-button { min-height: 68px; border-radius: 14px; border: 2px solid transparent; font-weight: 900; font-size: 1.15rem; }
.answer-button:disabled { cursor: not-allowed; opacity: .6; }
.answer-true { color: var(--good); background: var(--good-soft); border-color: #a7d8b8; }
.answer-false { color: var(--bad); background: var(--bad-soft); border-color: #efb7b7; }
.answer-button.is-selected { box-shadow: 0 0 0 4px rgba(47,93,124,.16); }
.quiz-feedback { border-radius: 14px; padding: 1rem 1.1rem; border: 1px solid var(--line); }
.quiz-feedback.correct { background: var(--good-soft); border-color: #a7d8b8; }
.quiz-feedback.incorrect { background: var(--bad-soft); border-color: #efb7b7; }
.quiz-feedback h3 { margin: 0 0 .35rem; }
.quiz-feedback p { margin: .35rem 0; }
.learner-note { border-left: 4px solid var(--gold); padding-left: .75rem; color: #574418; }
.quiz-summary { max-width: 760px; margin-inline: auto; text-align: center; }
.summary-score { font-size: 1.5rem; font-weight: 850; color: var(--navy); }
.missed-list { text-align: left; margin: 1rem auto; max-width: 620px; }
.missed-list ul { padding-left: 1.2rem; }
.missed-list li { margin: .35rem 0; }
.learn-footer { padding: 2rem 0 3rem; color: var(--muted); text-align: center; }
.error-panel { color: var(--bad); }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0; }
[hidden] { display: none !important; }
@media (max-width: 850px) {
  .control-grid, .quiz-control-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .controls-panel { position: static; }
}
@media (max-width: 620px) {
  .learn-header-inner { align-items: flex-start; flex-direction: column; padding-block: .8rem; }
  .learn-site-header nav { width: 100%; }
  .learn-site-header nav a { flex: 1; text-align: center; }
  .learn-hero { padding-top: 2.6rem; }
  .control-grid, .quiz-control-grid { grid-template-columns: 1fr; }
  .results-toolbar { align-items: stretch; flex-direction: column; }
  .vocab-card { grid-template-columns: 52px 1fr; }
  .vocab-gloss { grid-column: 2; }
  .vocab-meta, .vocab-details { grid-column: 1 / -1; }
  .answer-grid { grid-template-columns: 1fr; }
}

/* Vocabulary compact/full display modes */
.results-actions { display: flex; flex-wrap: wrap; gap: .65rem; align-items: center; }
.display-mode-control { display: inline-flex; padding: 3px; border: 1px solid #aebdca; border-radius: 11px; background: white; }
.mode-button { min-height: 36px; padding: .4rem .75rem; border: 0; border-radius: 8px; background: transparent; color: var(--blue); font-weight: 800; }
.mode-button:hover { background: var(--blue-soft); }
.mode-button[aria-pressed="true"] { background: var(--blue); color: white; }
.mode-help { margin: .65rem 0 0; color: var(--muted); font-size: .85rem; }
.vocab-rank { border: 0; font: inherit; cursor: pointer; }
.vocab-rank-toggle:hover { background: #d7e7f2; box-shadow: 0 0 0 3px rgba(47,93,124,.12); }
.vocab-rank-toggle[aria-expanded="true"] { background: var(--blue); color: white; }
.vocab-card.is-compact { align-items: center; padding-block: .72rem; }
.vocab-card.is-compact .vocab-extra { display: none; }
.vocab-card.is-compact .vocab-term,
.vocab-card.is-compact .vocab-gloss { align-self: center; }

@media (max-width: 620px) {
  .results-actions { align-items: stretch; flex-direction: column; }
  .display-mode-control { width: 100%; }
  .mode-button { flex: 1; }
  .vocab-card.is-compact { grid-template-columns: 48px minmax(0, .85fr) minmax(0, 1.15fr); gap: .65rem; padding: .7rem; }
  .vocab-card.is-compact .vocab-gloss { grid-column: auto; font-size: .94rem; }
}

/* Four-choice vocabulary quiz */
.multiple-choice-question-card { margin-bottom: 1.15rem; }
#mcq-term { color: var(--navy); }
.choice-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: .9rem; margin: 1.15rem 0; }
.choice-button { min-height: 74px; display: grid; grid-template-columns: 42px 1fr; align-items: center; gap: .8rem; padding: .75rem .95rem; border: 2px solid #bfd0dd; border-radius: 14px; background: white; color: var(--ink); text-align: left; font-weight: 780; transition: border-color .15s ease, background .15s ease, transform .15s ease; }
.choice-button:hover:not(:disabled) { border-color: var(--blue); background: var(--blue-soft); transform: translateY(-1px); }
.choice-button:disabled { cursor: not-allowed; }
.choice-letter { display: inline-flex; width: 38px; height: 38px; align-items: center; justify-content: center; border-radius: 999px; background: var(--canvas); color: var(--navy); border: 1px solid var(--line); font-weight: 900; }
.choice-text { line-height: 1.3; }
.choice-button.is-selected { box-shadow: 0 0 0 4px rgba(47,93,124,.15); }
.choice-button.is-correct { border-color: #75bc90; background: var(--good-soft); color: var(--good); }
.choice-button.is-correct .choice-letter { background: var(--good); border-color: var(--good); color: white; }
.choice-button.is-incorrect { border-color: #df8d8d; background: var(--bad-soft); color: var(--bad); }
.choice-button.is-incorrect .choice-letter { background: var(--bad); border-color: var(--bad); color: white; }

@media (max-width: 620px) {
  .choice-grid { grid-template-columns: 1fr; }
  .choice-button { min-height: 66px; }
}