:root {
  --bg: #f6f7f3;
  --panel: #ffffff;
  --ink: #1f2a24;
  --muted: #6d786f;
  --line: #dfe5df;
  --green: #186b4d;
  --green-soft: #e6f3ed;
  --amber: #a76a10;
  --amber-soft: #fff3dd;
  --red: #a33b3b;
  --red-soft: #fbe8e8;
  --shadow: 0 12px 40px rgba(26, 54, 39, 0.08);
}

* { box-sizing: border-box; }
body { margin: 0; font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif; background: var(--bg); color: var(--ink); }
button { font: inherit; }
.app-shell { min-height: 100vh; display: grid; grid-template-columns: 260px 1fr; }
.sidebar { border-right: 1px solid var(--line); background: #fbfcf9; padding: 24px 18px; position: sticky; top: 0; height: 100vh; }
.brand { display: flex; gap: 11px; align-items: center; margin-bottom: 28px; color: inherit; text-decoration: none; }
.brand-mark { width: 36px; height: 36px; border-radius: 10px; display: grid; place-items: center; background: var(--green); color: white; font-weight: 800; }
.brand h1 { font-size: 16px; margin: 0; }
.brand p { margin: 2px 0 0; font-size: 12px; color: var(--muted); }
.nav-btn { width: 100%; border: 0; background: transparent; text-align: left; padding: 11px 12px; border-radius: 9px; color: var(--ink); cursor: pointer; margin: 2px 0; display:block; text-decoration:none; }
.nav-btn:hover, .nav-btn.active { background: var(--green-soft); color: var(--green); font-weight: 650; }
.sidebar-note { margin-top: 28px; border: 1px solid var(--line); border-radius: 12px; padding: 12px; font-size: 12px; color: var(--muted); line-height: 1.45; }
.main { padding: 34px clamp(20px, 5vw, 70px) 70px; max-width: 1300px; width: 100%; }
.topline { display:flex; align-items:center; justify-content:space-between; gap:16px; margin-bottom: 26px; }
.eyebrow { color: var(--green); text-transform: uppercase; letter-spacing: .1em; font-size: 12px; font-weight: 750; }
h2 { font-size: clamp(28px, 4vw, 42px); line-height: 1.08; margin: 6px 0 10px; letter-spacing: -.03em; }
.lede { color: var(--muted); max-width: 760px; line-height: 1.6; margin: 0; }
.stat-strip { display:grid; grid-template-columns: repeat(3, minmax(0,1fr)); gap: 12px; margin: 26px 0; }
.stat { background: var(--panel); border: 1px solid var(--line); border-radius: 14px; padding: 16px; }
.stat strong { display:block; font-size: 25px; }
.stat span { color: var(--muted); font-size: 12px; }
.week-grid { display:grid; grid-template-columns: repeat(auto-fill, minmax(280px,1fr)); gap:16px; }
.card { background: var(--panel); border:1px solid var(--line); border-radius:16px; padding:18px; box-shadow: var(--shadow); }
.week-card { cursor:pointer; transition: transform .15s ease, border-color .15s ease; color:inherit; text-decoration:none; }
.week-card:hover { transform: translateY(-2px); border-color:#b9cabb; }
.card-head { display:flex; align-items:flex-start; justify-content:space-between; gap:12px; }
.badge { display:inline-flex; align-items:center; gap:6px; padding:5px 8px; border-radius:999px; font-size:11px; font-weight:700; }
.badge.verified { background: var(--green-soft); color: var(--green); }
.badge.provisional { background: var(--amber-soft); color: var(--amber); }
.badge.passed { background: var(--green-soft); color: var(--green); }
.section-list { display:grid; gap:10px; margin-top:16px; }
.section-row { display:flex; justify-content:space-between; align-items:center; gap:14px; border:1px solid var(--line); border-radius:12px; padding:13px; background:white; cursor:pointer; color:inherit; text-decoration:none; }
.section-row:hover { border-color:#aac2b0; }
.section-code { font-weight:800; color:var(--green); min-width:42px; }
.section-name { flex:1; }
.section-meta { color:var(--muted); font-size:12px; white-space:nowrap; }
.breadcrumb { color: var(--muted); font-size:13px; cursor:pointer; margin-bottom:16px; display:inline-block; text-decoration:none; }
.breadcrumb:hover { color:var(--green); }
.scope { margin:18px 0; padding:14px 16px; background:#f3f6f1; border-left:4px solid var(--green); border-radius:8px; color:#4f5e53; line-height:1.5; }
.primary, .secondary { border:0; border-radius:10px; padding:11px 16px; font-weight:750; cursor:pointer; }
.button-link { display:inline-flex; align-items:center; justify-content:center; text-decoration:none; }
.primary { background:var(--green); color:white; }
.secondary { background:#eef1ed; color:var(--ink); }
.quiz-wrap { max-width:820px; }
.quiz-progress { display:flex; gap:5px; margin:18px 0 24px; }
.quiz-progress span { height:6px; flex:1; border-radius:999px; background:#dfe5df; }
.quiz-progress span.done { background:var(--green); }
.quiz-progress span.current { background:#9ab7a1; }
.question-kicker { color:var(--muted); font-size:13px; margin-bottom:8px; }
.question { font-size:24px; line-height:1.35; font-weight:750; margin-bottom:20px; }
.choices { display:grid; gap:10px; }
.choice { width:100%; border:1px solid var(--line); background:white; border-radius:12px; padding:14px 16px; text-align:left; cursor:pointer; display:flex; gap:12px; align-items:flex-start; }
.choice:hover:not(:disabled) { border-color:#9ab7a1; background:#fbfdfb; }
.choice .letter { width:26px; height:26px; border-radius:7px; display:grid; place-items:center; background:#eff2ee; font-weight:800; flex:none; }
.choice.correct { border-color:#5f9f7d; background:var(--green-soft); }
.choice.wrong { border-color:#ce8d8d; background:var(--red-soft); }
.feedback { margin-top:16px; padding:15px 17px; border-radius:12px; line-height:1.55; }
.feedback.correct { background:var(--green-soft); color:#174c39; }
.feedback.wrong { background:var(--red-soft); color:#783434; }
.feedback .why { margin-top:8px; color:#435249; }
.quiz-actions { display:flex; justify-content:flex-end; margin-top:16px; }
.result-card { max-width:720px; text-align:center; padding:34px; }
.result-score { font-size:64px; line-height:1; font-weight:850; margin:15px 0; letter-spacing:-.05em; }
.result-actions { display:flex; justify-content:center; gap:10px; flex-wrap:wrap; margin-top:22px; }
.mistake-list { display:grid; gap:10px; }
.mistake { background:white; border:1px solid var(--line); border-radius:12px; padding:14px; }
.empty { border:1px dashed #c9d3ca; padding:30px; border-radius:14px; color:var(--muted); text-align:center; }
.small { font-size:12px; color:var(--muted); }
.mobile-menu { display:none; }
@media (max-width: 780px) {
  .app-shell { grid-template-columns:1fr; }
  .sidebar { position:static; height:auto; border-right:0; border-bottom:1px solid var(--line); padding:14px 16px; }
  .sidebar nav, .sidebar-note { display:none; }
  .brand { margin:0; }
  .main { padding:24px 16px 60px; }
  .stat-strip { grid-template-columns:1fr; }
}

.week-summary { margin-top:18px; color:var(--muted); font-size:13px; }
.spacer { height:20px; }
.mistake-actions { margin-top:10px; }
.mistake-actions a { color:var(--green); font-size:13px; font-weight:700; text-decoration:none; }
.mistake-actions a:hover { text-decoration:underline; }

/* Mastery / review enhancements */
.status-pill { display:inline-flex; align-items:center; white-space:nowrap; border-radius:999px; padding:4px 8px; font-size:11px; font-weight:750; line-height:1.2; }
.status-pill.not-started { background:#eef0ed; color:#687168; }
.status-pill.in-progress { background:var(--amber-soft); color:var(--amber); }
.status-pill.passed { background:var(--green-soft); color:var(--green); }
.status-pill.large { padding:7px 11px; font-size:12px; }
.section-heading-row { display:flex; align-items:flex-start; justify-content:space-between; gap:18px; }
.section-last-score { margin:-8px 0 18px; }
.week-card.week-complete { border-color:#a9cfb9; }
.mini-progress { height:7px; overflow:hidden; background:#e8ece8; border-radius:999px; margin:12px 0 9px; }
.mini-progress span { display:block; height:100%; border-radius:inherit; background:var(--green); transition:width .2s ease; }
.week-progress { max-width:620px; margin:12px 0 20px; }
.complete-summary { color:var(--green); }

.progress-weeks { display:grid; gap:20px; }
.progress-week { background:var(--panel); border:1px solid var(--line); border-radius:16px; padding:18px; }
.group-head { display:flex; align-items:flex-start; justify-content:space-between; gap:16px; }
.group-head h3 { margin:5px 0 0; }
.compact-list { margin-top:12px; }
.compact-list .section-row { padding:12px 10px; }
.progress-backup-actions { justify-content:flex-start; margin-top:18px; }

.mistake-group { margin:30px 0; }
.mistake-list { display:grid; gap:12px; margin-top:12px; }
.mistake { background:var(--panel); border:1px solid var(--line); border-radius:14px; padding:16px; }
.mistake.resolved { opacity:.78; }
.mistake-topline { display:flex; justify-content:space-between; gap:12px; align-items:center; margin-bottom:10px; }
.mistake-prompt { display:block; font-size:16px; line-height:1.5; }
.answer-compare { display:grid; grid-template-columns:repeat(2,minmax(0,1fr)); gap:10px; margin:14px 0; }
.answer-compare > div { background:#f7f8f5; border:1px solid var(--line); border-radius:10px; padding:11px; }
.answer-compare span { display:block; color:var(--muted); font-size:11px; text-transform:uppercase; letter-spacing:.06em; margin-bottom:4px; }
.answer-compare strong { display:block; font-size:13px; line-height:1.45; }
.mistake-actions { display:flex; align-items:center; gap:12px; flex-wrap:wrap; margin-top:14px; }
.mistake-actions a, .text-link { color:var(--green); font-weight:650; text-decoration:none; }
.why.compact { margin-top:10px; padding:10px 12px; background:#f6f8f5; border-radius:10px; line-height:1.5; }
.resolved-block { margin-top:28px; }
.resolved-block summary { cursor:pointer; color:var(--muted); font-weight:650; }
.success-empty { border-color:#b8d9c5; background:var(--green-soft); }

.result-card.passed-result { border-color:#a9cfb9; }
.result-card.failed-result { border-color:#e4bbbb; }
.result-breakdown { max-width:850px; margin:30px auto 0; }
.result-breakdown h3 { margin:6px 0 14px; }
.result-question { background:var(--panel); border:1px solid var(--line); border-radius:12px; margin:9px 0; overflow:hidden; }
.result-question.correct-row { border-left:4px solid var(--green); }
.result-question.wrong-row { border-left:4px solid var(--red); }
.result-question summary { display:flex; justify-content:space-between; gap:16px; padding:13px 14px; cursor:pointer; font-weight:700; }
.result-question-body { padding:0 14px 15px; line-height:1.5; }
.choice-notes { margin-top:10px; }
.choice-notes summary { padding:8px 0; font-size:13px; color:var(--green); }
.choice-notes ul { margin:4px 0 0; padding-left:22px; }
.choice-notes li { margin:7px 0; color:var(--muted); }
.choice-notes li.correct-option { color:var(--green); }

.error-text { color:var(--red) !important; }

@media (max-width: 720px) {
  .section-heading-row, .group-head { flex-direction:column; }
  .answer-compare { grid-template-columns:1fr; }
  .mistake-topline { align-items:flex-start; }
  .result-actions { align-items:stretch; }
  .result-actions > * { width:100%; text-align:center; }
}

/* KaTeX / mathematical content */
.math-content .katex { font-size: 1.02em; }
.question.math-content .katex { font-size: 1.06em; }
.choice .math-content { min-width: 0; }
.math-display { overflow-x: auto; overflow-y: hidden; padding: 8px 0; }
.math-display .katex-display { margin: .45em 0; }
.math-fallback { font-family: "STIX Two Math", "Cambria Math", serif; }
.answer-compare .katex { white-space: nowrap; }
.choice-notes .math-content { display: inline; }
@media (max-width: 560px) {
  .question.math-content { font-size: 21px; }
  .math-content .katex { font-size: .98em; }
}

/* Accessibility and mobile navigation polish */
.sr-only {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}
.skip-link {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 1000;
  transform: translateY(-160%);
  background: var(--ink);
  color: #fff;
  padding: 9px 12px;
  border-radius: 8px;
  text-decoration: none;
}
.skip-link:focus { transform: translateY(0); }
.sidebar-head { display:flex; align-items:center; justify-content:space-between; gap:12px; }
.sidebar-collapsible { display:block; }
button:focus-visible,
a:focus-visible,
summary:focus-visible,
[tabindex="-1"]:focus-visible {
  outline: 3px solid rgba(24, 107, 77, .32);
  outline-offset: 3px;
}
#main-content:focus { outline: none; }
.choice:focus-visible { border-color: var(--green); box-shadow: 0 0 0 3px rgba(24, 107, 77, .15); }
.choice:disabled { cursor: default; opacity: 1; }
.feedback:focus { outline: none; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: .01ms !important; animation-duration: .01ms !important; animation-iteration-count: 1 !important; }
}

@media (max-width: 780px) {
  .mobile-menu {
    display:grid;
    place-items:center;
    width:40px;
    height:40px;
    border:1px solid var(--line);
    border-radius:10px;
    background:var(--panel);
    color:var(--ink);
    cursor:pointer;
    flex:none;
  }
  .sidebar-head .brand { flex:1; }
  .sidebar-collapsible { display:none; padding-top:12px; }
  .sidebar-collapsible.open { display:block; }
  .sidebar nav { display:grid; }
  .sidebar .sidebar-note { display:block; margin-top:12px; }
  .question { overflow-wrap:anywhere; }
  .choice { padding:13px; }
}