:root {
  color-scheme: light;
  --ink: #171a35;
  --muted: #626780;
  --paper: #ffffff;
  --canvas: #f5f7fd;
  --line: #dfe3ef;
  --blue: #4f72c9;
  --blue-soft: #e9efff;
  --pink: #ad376f;
  --pink-soft: #fbeaf3;
  --mint: #16806f;
  --mint-soft: #e5f6f2;
  --gold: #a26413;
  --gold-soft: #fff3d9;
  --danger: #a83f52;
  --danger-soft: #fff0f2;
  --shadow: 0 18px 50px rgba(49, 57, 93, 0.09);
  font-family: Avenir, "Avenir Next", ui-rounded, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; background: var(--canvas); color: var(--ink); }
button, input { font: inherit; }
button { cursor: pointer; }

.skip-link { position: fixed; z-index: 100; top: 8px; left: 8px; transform: translateY(-160%); background: var(--ink); color: white; padding: 10px 14px; }
.skip-link:focus { transform: none; }
.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; }

.topbar { position: sticky; z-index: 20; top: 0; min-height: 76px; display: grid; grid-template-columns: 190px 1fr auto; align-items: center; gap: 24px; padding: 10px 28px; border-bottom: 1px solid rgba(213,218,232,.8); background: rgba(255,255,255,.94); backdrop-filter: blur(18px); }
.brand { display: inline-flex; width: 132px; height: 48px; align-items: center; }
.brand img { display: block; width: 100%; height: auto; }
.topbar-title { display: flex; align-items: baseline; gap: 10px; min-width: 0; }
.topbar-title span { color: var(--pink); font-size: 12px; font-weight: 800; text-transform: uppercase; }
.topbar-title strong { font-size: 17px; }
.progress-summary { display: grid; grid-template-columns: auto 116px; align-items: center; gap: 12px; color: var(--muted); font-size: 13px; font-weight: 700; }
.progress-track { width: 116px; height: 7px; overflow: hidden; border-radius: 4px; background: #e6e9f2; }
.progress-track span { display: block; height: 100%; width: 12.5%; background: var(--blue); transition: width .25s ease; }

.app-shell { display: grid; grid-template-columns: 270px minmax(0, 1fr); min-height: calc(100vh - 76px); }
.lesson-nav { position: sticky; top: 76px; align-self: start; height: calc(100vh - 76px); padding: 34px 24px; border-right: 1px solid var(--line); background: #fbfcff; overflow-y: auto; }
.nav-eyebrow { margin: 0 0 16px 10px; color: var(--muted); font-size: 11px; font-weight: 800; text-transform: uppercase; }
.module-back { display: inline-flex; margin: 0 0 18px 10px; color: #304f9c; font-size: 13px; font-weight: 850; text-decoration: none; }
.module-back:hover { text-decoration: underline; }
.lesson-nav nav { display: grid; gap: 5px; }
.nav-step { width: 100%; min-height: 48px; display: grid; grid-template-columns: 28px 1fr; align-items: center; gap: 10px; padding: 8px 10px; border: 0; border-radius: 7px; background: transparent; color: var(--muted); text-align: left; }
.nav-step:hover { background: #f0f2f9; color: var(--ink); }
.nav-step.active { background: var(--blue-soft); color: #304f9c; font-weight: 800; }
.nav-step.visited .step-number { background: var(--mint); color: white; }
.step-number { display: grid; width: 28px; height: 28px; place-items: center; border-radius: 50%; background: #e8eaf2; color: #5f6376; font-size: 12px; font-weight: 800; }
.saved-note { display: flex; gap: 10px; align-items: flex-start; margin-top: 26px; padding: 14px; border-top: 1px solid var(--line); color: var(--muted); font-size: 12px; line-height: 1.4; }
.saved-note > span { display: grid; flex: 0 0 24px; height: 24px; place-items: center; border-radius: 50%; background: var(--mint-soft); color: var(--mint); font-weight: 900; }
.saved-note p { margin: 0; }
.saved-note strong { display: block; color: var(--ink); }

.lesson-main { width: min(940px, calc(100% - 48px)); margin: 0 auto; padding: 54px 0 42px; outline: none; }
.lesson-hero { position: relative; overflow: hidden; min-height: 360px; display: flex; flex-direction: column; justify-content: flex-end; padding: 46px; border: 1px solid #d9deeb; border-radius: 8px; background: var(--paper); box-shadow: var(--shadow); }
.lesson-hero::after { content: "word"; position: absolute; top: -54px; right: -20px; color: #eef1fa; font-size: 210px; font-weight: 900; line-height: 1; pointer-events: none; }
.lesson-hero > * { position: relative; z-index: 1; }
.language-hero::after { content: "abc"; }
.eyebrow { margin: 0 0 12px; color: var(--pink); font-size: 12px; font-weight: 900; text-transform: uppercase; }
h1, h2, h3, p { letter-spacing: 0; }
h1 { max-width: 720px; margin: 0; font-size: clamp(42px, 7vw, 78px); line-height: .98; }
.lead { max-width: 700px; margin: 22px 0 0; color: var(--muted); font-size: 20px; line-height: 1.55; }
.lesson-heading { max-width: 760px; margin-bottom: 32px; }
.lesson-heading h1 { font-size: clamp(36px, 5.2vw, 62px); }
.lesson-heading .lead { font-size: 18px; }

.goal-strip { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin-top: 18px; }
.goal { padding: 18px; border-left: 4px solid var(--blue); background: var(--paper); }
.goal:nth-child(2) { border-color: var(--pink); }
.goal:nth-child(3) { border-color: #e3a438; }
.goal strong { display: block; margin-bottom: 5px; }
.goal span { color: var(--muted); font-size: 14px; line-height: 1.45; }

.content-band { margin: 18px 0; padding: 28px; border: 1px solid var(--line); border-radius: 8px; background: var(--paper); }
.content-band h2 { margin: 0 0 8px; font-size: 28px; }
.content-band h3 { margin: 0 0 8px; font-size: 21px; }
.content-band > p, .content-band li { color: var(--muted); line-height: 1.6; }
.content-band > p { margin: 8px 0; }
.content-band ul { margin: 14px 0 0; padding-left: 22px; }
.content-band li + li { margin-top: 5px; }
.band-accent { background: var(--blue-soft); border-color: #cdd9fb; }
.band-pink { background: var(--pink-soft); border-color: #f2cfe0; }
.band-gold { background: var(--gold-soft); border-color: #f2dca8; }
.band-mint { background: var(--mint-soft); border-color: #bde7dc; }

.word-orbit { display: flex; flex-wrap: wrap; align-items: center; gap: 9px; margin: 22px 0 0; }
.word-orbit span { padding: 11px 14px; border: 1px solid #ced7ef; border-radius: 6px; background: white; color: #304f9c; font-weight: 800; }
.word-orbit i { color: var(--pink); font-style: normal; font-weight: 900; }
.role-grid, .suffix-grid, .strategy-grid { display: grid; grid-template-columns: repeat(2, minmax(0,1fr)); gap: 14px; margin-top: 18px; }
.role, .suffix, .strategy-step { padding: 22px; border: 1px solid var(--line); border-radius: 8px; background: var(--paper); }
.role header, .suffix header { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.role h3, .suffix h3 { margin: 0; font-size: 20px; }
.role-mark { color: var(--pink); font-size: 13px; font-weight: 900; }
.role p, .suffix p, .strategy-step p { margin: 10px 0 0; color: var(--muted); line-height: 1.55; }
.examples { display: grid; gap: 7px; margin-top: 14px; }
.examples code { padding: 8px 10px; border-radius: 5px; background: #f4f6fb; color: var(--ink); font-family: inherit; font-size: 14px; }

.family-table { width: 100%; margin-top: 18px; border-collapse: collapse; background: var(--paper); }
.family-table th, .family-table td { padding: 13px 14px; border-bottom: 1px solid var(--line); text-align: left; }
.family-table th { color: var(--muted); font-size: 12px; text-transform: uppercase; }
.family-table tr:last-child td { border-bottom: 0; }
.family-table strong { color: var(--blue); }
.table-scroll { overflow-x: auto; border: 1px solid var(--line); border-radius: 8px; }

.checkpoint { margin-top: 24px; padding: 24px; border: 1px solid #ccd7f1; border-radius: 8px; background: #f9fbff; }
.checkpoint-tag { margin: 0 0 5px; color: var(--blue); font-size: 11px; font-weight: 900; text-transform: uppercase; }
.checkpoint h2 { margin: 0 0 16px; font-size: 21px; }
.choice-list { display: grid; gap: 9px; }
.choice { min-height: 48px; padding: 12px 14px; border: 1px solid var(--line); border-radius: 6px; background: white; color: var(--ink); text-align: left; }
.choice:hover { border-color: var(--blue); }
.choice.selected { border-color: var(--blue); background: var(--blue-soft); }
.choice.correct { border-color: var(--mint); background: var(--mint-soft); }
.choice.incorrect { border-color: var(--danger); background: var(--danger-soft); }
.feedback { display: none; margin-top: 12px; padding: 12px 14px; border-left: 4px solid var(--blue); background: white; color: var(--muted); line-height: 1.5; }
.feedback.visible { display: block; }
.feedback.correct { border-color: var(--mint); color: #0d6558; }
.feedback.incorrect { border-color: var(--danger); color: #8b3143; }

.practice-intro { display: flex; justify-content: space-between; gap: 20px; align-items: end; margin-bottom: 24px; }
.practice-score { flex: 0 0 auto; padding: 14px 18px; border-radius: 7px; background: var(--ink); color: white; text-align: center; }
.practice-score strong { display: block; font-size: 24px; }
.practice-score span { font-size: 11px; text-transform: uppercase; }
.exercise-group { margin: 16px 0; padding: 26px; border: 1px solid var(--line); border-radius: 8px; background: var(--paper); }
.exercise-group > header { display: flex; justify-content: space-between; gap: 16px; align-items: start; margin-bottom: 20px; }
.exercise-group h2 { margin: 0; font-size: 25px; }
.exercise-group header p { margin: 6px 0 0; color: var(--muted); }
.exercise-count { color: var(--pink); font-size: 12px; font-weight: 900; text-transform: uppercase; white-space: nowrap; }
.question-list { display: grid; gap: 12px; }
.question { position: relative; padding: 16px; border: 1px solid var(--line); border-radius: 7px; background: #fbfcff; }
.question label { display: block; color: var(--ink); line-height: 1.55; }
.choice-question > p { margin: 0 0 12px; font-weight: 750; line-height: 1.5; }
.question input { width: 100%; min-height: 45px; margin-top: 10px; padding: 10px 12px; border: 1px solid #bfc6d9; border-radius: 5px; background: white; color: var(--ink); }
.question input:focus { outline: 3px solid rgba(79,114,201,.22); border-color: var(--blue); }
.question.correct { border-color: var(--mint); background: var(--mint-soft); }
.question.incorrect { border-color: var(--danger); background: var(--danger-soft); }
.question-note { display: none; margin: 8px 0 0; color: var(--muted); font-size: 13px; line-height: 1.45; }
.question.checked .question-note { display: block; }
.context-text { font-size: 17px; line-height: 1.9; }
.context-gap { display: inline-grid; grid-template-columns: minmax(120px,180px); margin: 3px 5px; vertical-align: middle; }
.context-gap input { min-height: 38px; padding: 5px 8px; border: 0; border-bottom: 2px solid #9ba6c3; background: transparent; }
.context-gap input:focus { outline: 2px solid var(--blue); outline-offset: 2px; }
.base-word { color: var(--pink); font-size: 12px; font-weight: 900; }
.group-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 18px; }

.button { min-height: 46px; display: inline-flex; align-items: center; justify-content: center; gap: 8px; padding: 11px 18px; border: 1px solid transparent; border-radius: 6px; font-weight: 800; }
.button.primary { background: var(--ink); color: white; }
.button.primary:hover { background: #2a2e51; }
.button.secondary { border-color: #bfc6d7; background: white; color: var(--ink); }
.button.ghost { border-color: transparent; background: transparent; color: var(--blue); }
.button:focus-visible, .nav-step:focus-visible, .choice:focus-visible { outline: 3px solid rgba(79,114,201,.35); outline-offset: 2px; }
.lesson-actions { display: flex; justify-content: space-between; gap: 12px; padding-top: 24px; }
.button:disabled { cursor: not-allowed; opacity: .45; }

.summary { padding: 40px; border: 1px solid var(--line); border-radius: 8px; background: white; box-shadow: var(--shadow); }
.summary-score { display: grid; width: 126px; height: 126px; place-items: center; margin-bottom: 24px; border-radius: 50%; background: var(--mint-soft); color: var(--mint); }
.summary-score strong { font-size: 36px; }
.summary h1 { font-size: clamp(38px, 6vw, 64px); }
.summary-grid { display: grid; grid-template-columns: repeat(3,1fr); gap: 12px; margin: 26px 0; }
.summary-stat { padding: 18px; border: 1px solid var(--line); border-radius: 7px; }
.summary-stat strong { display: block; font-size: 25px; }
.summary-stat span { color: var(--muted); font-size: 13px; }
.reference-list { columns: 2; column-gap: 24px; margin-top: 18px; }
.reference-list p { break-inside: avoid; margin: 0 0 10px; padding: 11px; border-left: 3px solid var(--pink); background: #faf7fb; color: var(--muted); }

@media (max-width: 820px) {
  .topbar { grid-template-columns: auto 1fr; padding: 9px 18px; }
  .brand { width: 110px; }
  .topbar-title { justify-self: end; }
  .topbar-title span { display: none; }
  .progress-summary { grid-column: 1 / -1; grid-template-columns: auto 1fr; }
  .progress-track { width: 100%; }
  .app-shell { display: block; }
  .lesson-nav { position: sticky; z-index: 12; top: 89px; width: 100%; height: auto; padding: 8px 14px; border-right: 0; border-bottom: 1px solid var(--line); overflow: auto hidden; }
  .nav-eyebrow, .saved-note { display: none; }
  .module-back { flex: 0 0 auto; margin: 0 7px 0 0; align-items: center; white-space: nowrap; }
  .lesson-nav nav { display: flex; width: max-content; gap: 5px; }
  .nav-step { width: auto; grid-template-columns: 28px auto; white-space: nowrap; }
  .lesson-main { width: min(100% - 30px, 720px); padding-top: 28px; }
  .lesson-hero { min-height: 390px; padding: 28px; }
  .lesson-hero::after { top: 0; font-size: 112px; }
  .goal-strip, .role-grid, .suffix-grid, .strategy-grid, .summary-grid { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
  .topbar-title strong { font-size: 14px; }
  .lesson-nav { top: 91px; }
  .lesson-main { width: min(100% - 24px, 720px); }
  .lesson-hero, .content-band, .exercise-group, .summary { padding: 20px; }
  h1 { font-size: 40px; }
  .lesson-heading h1 { font-size: 36px; }
  .lead { font-size: 17px; }
  .practice-intro, .exercise-group > header { display: block; }
  .practice-score { width: max-content; margin-top: 14px; }
  .exercise-count { display: block; margin-top: 8px; }
  .family-table th, .family-table td { padding: 10px; }
  .reference-list { columns: 1; }
  .lesson-actions { padding-bottom: 0; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: .01ms !important; }
}

@media (forced-colors: active) {
  .nav-step.active, .choice.selected, .question.correct, .question.incorrect { border: 2px solid CanvasText; }
  .progress-track span { background: Highlight; }
}