:root {
  --clay: #d97757;
  --clay-dark: #c15f3f;
  --ink: #1f1b16;
  --paper: #f7f4ef;
  --card: #ffffff;
  --muted: #6b6259;
  --line: #e7e0d6;
  --good: #2e7d5b;
  --good-bg: #e7f3ec;
  --bad: #c0392b;
  --bad-bg: #fbeae7;
  --shadow: 0 1px 2px rgba(31, 27, 22, 0.06), 0 8px 24px rgba(31, 27, 22, 0.06);
  --radius: 14px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --ink: #f2ede5;
    --paper: #1a1714;
    --card: #241f1b;
    --muted: #a89e92;
    --line: #362f28;
    --good: #6fcf97;
    --good-bg: #1e3329;
    --bad: #e88a7d;
    --bad-bg: #3a221f;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 8px 24px rgba(0, 0, 0, 0.35);
  }
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
}

a { color: var(--clay-dark); }

.layout { display: flex; min-height: 100vh; }

/* Sidebar */
.sidebar {
  width: 300px;
  flex-shrink: 0;
  background: var(--card);
  border-right: 1px solid var(--line);
  padding: 22px 18px;
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
}
.brand { display: flex; align-items: center; gap: 10px; margin-bottom: 6px; }
.brand .logo {
  width: 34px; height: 34px; border-radius: 9px;
  background: var(--clay); color: #fff; display: grid; place-items: center;
  font-weight: 700; font-size: 18px;
}
.brand h1 { font-size: 16px; margin: 0; line-height: 1.2; }
.brand small { color: var(--muted); font-size: 12px; }
.lang-btn {
  margin-left: auto; flex-shrink: 0; border: 1px solid var(--line);
  background: var(--paper); color: var(--muted); border-radius: 8px;
  padding: 4px 9px; font-size: 12px; font-weight: 700; cursor: pointer;
  letter-spacing: .03em;
}
.lang-btn:hover { border-color: var(--clay); color: var(--clay-dark); }

.progress-global {
  margin: 16px 0 20px; padding: 12px; border: 1px solid var(--line);
  border-radius: 10px; background: var(--paper);
}
.progress-global .bar { height: 8px; background: var(--line); border-radius: 99px; overflow: hidden; margin-top: 8px; }
.progress-global .bar > span { display: block; height: 100%; background: var(--clay); width: 0; transition: width .4s ease; }
.progress-global .label { font-size: 12px; color: var(--muted); display: flex; justify-content: space-between; }

.course-group { margin-bottom: 18px; }
.course-group > .course-title {
  font-size: 12px; text-transform: uppercase; letter-spacing: .06em;
  color: var(--muted); font-weight: 700; margin: 0 6px 8px;
}
.nav-item {
  display: flex; align-items: center; gap: 10px; width: 100%;
  text-align: left; border: none; background: transparent; color: var(--ink);
  padding: 9px 10px; border-radius: 9px; cursor: pointer; font-size: 14px;
}
.nav-item:hover { background: var(--paper); }
.nav-item.active { background: var(--clay); color: #fff; }
.nav-item .dot {
  width: 8px; height: 8px; border-radius: 99px; background: var(--line); flex-shrink: 0;
}
.nav-item.done .dot { background: var(--good); }
.nav-item.active .dot { background: rgba(255,255,255,.7); }
.nav-item .txt { flex: 1; min-width: 0; }
.nav-item .score { font-size: 11px; color: var(--muted); }
.nav-item.active .score { color: rgba(255,255,255,.85); }

.sidebar .foot { margin-top: 22px; font-size: 11px; color: var(--muted); line-height: 1.5; }
.reset-btn {
  margin-top: 10px; border: 1px solid var(--line); background: transparent; color: var(--muted);
  border-radius: 8px; padding: 6px 10px; font-size: 12px; cursor: pointer;
}
.reset-btn:hover { color: var(--bad); border-color: var(--bad); }

/* Main */
.main { flex: 1; min-width: 0; padding: 34px clamp(18px, 5vw, 64px); max-width: 900px; }
.crumbs { font-size: 13px; color: var(--muted); margin-bottom: 6px; }
.module-head h2 { font-size: 28px; margin: 0 0 6px; }
.module-head .summary { color: var(--muted); margin: 0 0 18px; }

.tabs { display: flex; gap: 6px; border-bottom: 1px solid var(--line); margin-bottom: 26px; }
.tab {
  border: none; background: transparent; color: var(--muted); cursor: pointer;
  padding: 10px 14px; font-size: 15px; font-weight: 600; border-bottom: 2px solid transparent;
  margin-bottom: -1px;
}
.tab:hover { color: var(--ink); }
.tab.active { color: var(--clay-dark); border-bottom-color: var(--clay); }

/* Doc content */
.doc h3 { font-size: 19px; margin: 28px 0 10px; }
.doc h3:first-child { margin-top: 0; }
.doc p { margin: 10px 0; }
.doc ul, .doc ol { margin: 10px 0; padding-left: 22px; }
.doc li { margin: 4px 0; }
.doc blockquote {
  margin: 14px 0; padding: 12px 16px; border-left: 3px solid var(--clay);
  background: var(--card); border-radius: 0 10px 10px 0;
}
.doc code {
  background: var(--card); border: 1px solid var(--line); border-radius: 5px;
  padding: 1px 5px; font-size: 13px; font-family: "SFMono-Regular", Menlo, Consolas, monospace;
}
.doc pre {
  background: var(--ink); color: #f5efe6; padding: 16px; border-radius: 10px;
  overflow-x: auto; margin: 14px 0;
}
.doc pre code { background: transparent; border: none; color: inherit; padding: 0; font-size: 13px; }
.doc table { width: 100%; border-collapse: collapse; margin: 14px 0; font-size: 14px; }
.doc th, .doc td { border: 1px solid var(--line); padding: 8px 10px; text-align: left; vertical-align: top; }
.doc th { background: var(--card); }
.doc-actions { margin-top: 30px; padding-top: 18px; border-top: 1px solid var(--line); }

/* Buttons */
.btn {
  border: none; border-radius: 10px; padding: 11px 20px; font-size: 15px; font-weight: 600;
  cursor: pointer; background: var(--clay); color: #fff;
}
.btn:hover { background: var(--clay-dark); }
.btn:disabled { opacity: .5; cursor: not-allowed; }
.btn.ghost { background: transparent; color: var(--clay-dark); border: 1px solid var(--line); }
.btn.ghost:hover { background: var(--card); }

/* Quiz */
.quiz-top { display: flex; justify-content: space-between; align-items: center; margin-bottom: 18px; }
.quiz-top .qcount { font-size: 14px; color: var(--muted); }
.qbar { height: 6px; background: var(--line); border-radius: 99px; overflow: hidden; margin-bottom: 26px; }
.qbar > span { display: block; height: 100%; background: var(--clay); transition: width .3s; }

.question { font-size: 20px; font-weight: 650; margin: 0 0 20px; line-height: 1.4; }
.options { display: flex; flex-direction: column; gap: 10px; }
.option {
  display: flex; align-items: flex-start; gap: 12px; text-align: left;
  border: 1.5px solid var(--line); background: var(--card); color: var(--ink);
  border-radius: 11px; padding: 14px 16px; cursor: pointer; font-size: 15px; width: 100%;
  transition: border-color .15s, background .15s;
}
.option:hover:not(:disabled) { border-color: var(--clay); }
.option .key {
  width: 24px; height: 24px; flex-shrink: 0; border-radius: 6px; background: var(--paper);
  border: 1px solid var(--line); display: grid; place-items: center; font-size: 13px; font-weight: 700;
}
.option.correct { border-color: var(--good); background: var(--good-bg); }
.option.correct .key { background: var(--good); color: #fff; border-color: var(--good); }
.option.wrong { border-color: var(--bad); background: var(--bad-bg); }
.option.wrong .key { background: var(--bad); color: #fff; border-color: var(--bad); }
.option:disabled { cursor: default; }

.feedback {
  margin-top: 18px; padding: 14px 16px; border-radius: 11px; font-size: 14px;
  border: 1px solid var(--line); background: var(--card);
}
.feedback.ok { border-color: var(--good); background: var(--good-bg); }
.feedback.no { border-color: var(--bad); background: var(--bad-bg); }
.feedback .verdict { font-weight: 700; display: block; margin-bottom: 4px; }
.quiz-nav { margin-top: 26px; display: flex; justify-content: flex-end; gap: 10px; }

/* Results */
.results { text-align: center; padding: 20px 0; }
.results .ring { width: 150px; height: 150px; margin: 10px auto 18px; position: relative; }
.results .ring svg { transform: rotate(-90deg); }
.results .ring .pct {
  position: absolute; inset: 0; display: grid; place-items: center;
  font-size: 34px; font-weight: 800;
}
.results h2 { margin: 0 0 6px; }
.results .verdict-msg { color: var(--muted); margin-bottom: 24px; }
.review { text-align: left; margin-top: 24px; }
.review h3 { font-size: 16px; margin-bottom: 12px; }
.review-item {
  border: 1px solid var(--line); border-radius: 10px; padding: 12px 14px; margin-bottom: 10px;
  background: var(--card); font-size: 14px;
}
.review-item .q { font-weight: 650; margin-bottom: 6px; }
.review-item .a { color: var(--muted); }
.review-item .tag { font-size: 11px; font-weight: 700; padding: 2px 8px; border-radius: 99px; }
.tag.ok { color: var(--good); background: var(--good-bg); }
.tag.no { color: var(--bad); background: var(--bad-bg); }
.results-actions { display: flex; gap: 10px; justify-content: center; margin-top: 8px; }

/* Welcome */
.welcome { max-width: 720px; }
.welcome h2 { font-size: 30px; margin-bottom: 8px; }
.welcome .lead { color: var(--muted); font-size: 17px; margin-bottom: 28px; }
.cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(230px,1fr)); gap: 14px; }
.ccard {
  border: 1px solid var(--line); border-radius: var(--radius); padding: 18px; background: var(--card);
  box-shadow: var(--shadow); cursor: pointer;
}
.ccard:hover { border-color: var(--clay); }
.ccard .ic { font-size: 26px; }
.ccard h3 { margin: 8px 0 4px; font-size: 17px; }
.ccard p { margin: 0; font-size: 13px; color: var(--muted); }
.ccard .meta { margin-top: 12px; font-size: 12px; color: var(--muted); }

.mobile-toggle { display: none; }

@media (max-width: 820px) {
  .layout { flex-direction: column; }
  .sidebar {
    position: static; width: auto; height: auto; border-right: none; border-bottom: 1px solid var(--line);
  }
  .main { padding: 24px 18px; }
}