/* Mobile first. Light and dark follow the system setting. */
:root {
  --bg: #ffffff;
  --fg: #1b1c1f;
  --muted: #545b66;
  --line: #d5d9df;
  --card: #f5f6f8;
  --accent: #0b6e4f;
  --accent-fg: #ffffff;
  --accent-soft: #e2f1eb;
  --good: #11713d;
  --good-bg: #e5f3ea;
  --bad: #b3261e;
  --bad-bg: #fcebe9;
  --focus: #1a5fd0;
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #121416;
    --fg: #e8eaed;
    --muted: #a9b0b9;
    --line: #353a41;
    --card: #1b1e22;
    --accent: #52c49b;
    --accent-fg: #0b1a14;
    --accent-soft: #163128;
    --good: #63d39c;
    --good-bg: #143223;
    --bad: #ff8b80;
    --bad-bg: #3c1b18;
    --focus: #8ab4ff;
  }
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font: 17px/1.55 system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: var(--bg);
  color: var(--fg);
}
a { color: var(--accent); text-underline-offset: 2px; }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; }
[tabindex="-1"]:focus { outline: none; }

.wrap { max-width: 48rem; margin: 0 auto; padding: 0 1rem; }
.wide .wrap { max-width: 76rem; }
.skip { position: absolute; left: -999px; top: 0; }
.skip:focus { left: 1rem; top: 1rem; background: var(--bg); padding: .5rem .75rem; z-index: 10; }

h1 { font-size: 1.8rem; line-height: 1.2; margin: 1.5rem 0 .75rem; }
h2 { font-size: 1.35rem; line-height: 1.3; margin: 2rem 0 .75rem; }
h3 { font-size: 1.1rem; margin: 1.25rem 0 .5rem; }
.lead { font-size: 1.12rem; }
.muted { color: var(--muted); }
.small { font-size: .9rem; }
.source { font-size: .9rem; color: var(--muted); }
.subtitle { color: var(--muted); margin-top: -.25rem; }

/* header and footer */
.site-header { border-bottom: 1px solid var(--line); }
.bar { display: flex; flex-wrap: wrap; align-items: center; gap: .4rem 1.25rem; padding-top: .7rem; padding-bottom: .7rem; }
.brand { font-weight: 700; color: var(--fg); text-decoration: none; margin-right: auto; }
.mainnav, .langs, .legal { display: flex; flex-wrap: wrap; gap: .25rem .9rem; }
.langs a { text-decoration: none; padding: .15rem .35rem; border-radius: .3rem; }
.langs a[aria-current], .mainnav a[aria-current] { font-weight: 700; }
.langs a[aria-current] { background: var(--accent-soft); }
.site-footer { border-top: 1px solid var(--line); margin-top: 3rem; padding: 1.25rem 0 2rem; font-size: .92rem; color: var(--muted); }
.disclaimer { color: var(--fg); font-weight: 600; }

/* buttons and cards */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  min-height: 48px; padding: .6rem 1.1rem;
  background: var(--accent); color: var(--accent-fg);
  border: 2px solid var(--accent); border-radius: .55rem;
  font: inherit; font-weight: 600; text-decoration: none; cursor: pointer;
}
.btn.secondary { background: transparent; color: var(--accent); }
.btn:disabled { opacity: .55; cursor: not-allowed; }
.link { background: none; border: 0; padding: .5rem 0; min-height: 44px; color: var(--accent); font: inherit; text-decoration: underline; cursor: pointer; }
.cta { display: flex; flex-wrap: wrap; gap: .75rem; margin: 1.25rem 0 .5rem; }
.card { background: var(--card); border: 1px solid var(--line); border-radius: .75rem; padding: 1rem 1.1rem; margin: .9rem 0; }
.card > :first-child { margin-top: 0; }
.card.featured { border: 2px solid var(--accent); }
.grid2 { display: grid; gap: 1rem; }
.grid2 .card { margin: 0; }
@media (min-width: 720px) { .grid2 { grid-template-columns: 1fr 1fr; } }
.facts li, .steps li, .card li { margin: .3rem 0; }
.dates { font-size: 1.1rem; font-weight: 600; }
details.faq { border-bottom: 1px solid var(--line); padding: .7rem 0; }
details.faq summary { cursor: pointer; font-weight: 600; }
details.faq p { margin: .5rem 0 0; }

/* language chooser */
.chooser h1 { margin-top: 2.5rem; }
.langcards { list-style: none; padding: 0; display: grid; gap: .9rem; }
@media (min-width: 720px) { .langcards { grid-template-columns: 1fr 1fr; } }
.langcards a { display: flex; flex-direction: column; gap: .2rem; padding: 1rem 1.1rem; border: 1px solid var(--line); border-radius: .75rem; background: var(--card); color: var(--fg); text-decoration: none; }
.langcards a:hover { border-color: var(--accent); }
.langcards strong { color: var(--accent); font-size: 1.15rem; }

/* trainer */
.app-title { font-size: 1.5rem; }
.toolbar { display: flex; flex-wrap: wrap; align-items: center; gap: .5rem; margin: .5rem 0 1rem; }
select, input[type="text"] {
  font: inherit; color: var(--fg); background: var(--bg);
  border: 1px solid var(--muted); border-radius: .45rem;
  padding: .5rem .6rem; min-height: 44px; max-width: 100%;
}
.unlock { display: flex; flex-wrap: wrap; align-items: center; gap: .6rem; }
.unlock label { flex-basis: 100%; font-weight: 600; }
.unlock input { flex: 1 1 16rem; }
.check { display: inline-flex; align-items: center; gap: .4rem; cursor: pointer; }
.check input { width: 1.25rem; height: 1.25rem; }
.notice { background: var(--accent-soft); padding: .6rem .8rem; border-radius: .5rem; }
.ok-note { color: var(--good); font-weight: 600; }
.error { color: var(--bad); font-weight: 600; }
.qhead { display: flex; flex-wrap: wrap; align-items: baseline; gap: .25rem 1rem; }
.qhead h2 { margin: 1rem auto .25rem 0; }
.timer { font-weight: 700; font-variant-numeric: tabular-nums; margin: 0; }
.question .lt { font-size: 1.15rem; font-weight: 600; margin: .5rem 0 .3rem; }
.tr { color: var(--muted); }
.question .tr { margin-top: 0; }
.options { display: grid; gap: .6rem; margin: 1rem 0; }
.opt {
  display: block; width: 100%; min-height: 48px; padding: .7rem .9rem;
  text-align: left; font: inherit; color: var(--fg); background: var(--bg);
  border: 2px solid var(--line); border-radius: .6rem; cursor: pointer;
}
.opt:hover:not(:disabled) { border-color: var(--accent); }
.opt .tr { display: block; font-size: .95rem; margin-top: .15rem; }
.opt[aria-pressed="true"] { border-color: var(--accent); background: var(--accent-soft); }
.opt:disabled { cursor: default; opacity: 1; color: var(--fg); }
.opt.right { border-color: var(--good); background: var(--good-bg); }
.opt.wrong { border-color: var(--bad); background: var(--bad-bg); }
.tag { display: block; margin-top: .3rem; font-size: .85rem; font-weight: 700; }
.opt.right .tag { color: var(--good); }
.opt.wrong .tag { color: var(--bad); }
.feedback { border-left: 4px solid var(--line); padding: .1rem 0 .1rem .9rem; margin: 1rem 0; }
.verdict { font-weight: 700; }
.verdict.good { color: var(--good); }
.verdict.bad { color: var(--bad); }
.links { display: flex; flex-wrap: wrap; gap: .25rem 1.25rem; }
.score { font-size: 1.4rem; font-weight: 700; margin: .5rem 0; }
.passline { font-size: 1.05rem; }
.upsell h3 { font-size: 1.2rem; }
.ticks { list-style: none; padding-left: 0; }
.ticks li { position: relative; padding-left: 1.6rem; }
.ticks li::before { content: "\2713"; position: absolute; left: .1rem; color: var(--accent); font-weight: 700; }
.price-line { font-weight: 700; margin-bottom: .25rem; }
.btn.big { min-height: 54px; padding: .75rem 1.4rem; font-size: 1.1rem; }
.review { padding-left: 1.3rem; }
.review li { padding: .5rem 0 .75rem; border-bottom: 1px solid var(--line); }
.review li p { margin: .3rem 0; }
.chapters { list-style: none; padding: 0; display: grid; gap: .6rem; }
.chapter-btn {
  display: flex; flex-direction: column; gap: .15rem; width: 100%; min-height: 48px;
  padding: .7rem .9rem; text-align: left; font: inherit; color: var(--fg);
  background: var(--card); border: 1px solid var(--line); border-radius: .6rem; cursor: pointer;
}
.chapter-btn:hover { border-color: var(--accent); }
.ch-title { font-weight: 600; }
.table-wrap { overflow-x: auto; }
table { border-collapse: collapse; width: 100%; font-size: .95rem; }
th, td { text-align: left; padding: .45rem .4rem; border-bottom: 1px solid var(--line); vertical-align: top; }
td { white-space: nowrap; }

/* reader */
.toc ol { padding-left: 1.3rem; }
.toc li { margin: .25rem 0; }
.chapter > h2 { border-top: 2px solid var(--line); padding-top: 1rem; }
.art { border-top: 1px solid var(--line); padding: .25rem 0 .75rem; scroll-margin-top: .5rem; }
.art:target { background: var(--accent-soft); box-shadow: 0 0 0 .5rem var(--accent-soft); border-radius: .25rem; }
.art h3 a { color: var(--fg); text-decoration: none; }
.art h3 a:hover { text-decoration: underline; }
.tr-h { color: var(--muted); font-weight: 400; }
.cols { display: grid; gap: 0 2rem; }
.cols .tr { color: var(--fg); border-left: 3px solid var(--line); padding-left: .75rem; }
@media (min-width: 900px) {
  .cols.two { grid-template-columns: 1fr 1fr; }
  .cols.two .tr { border-left: 0; padding-left: 0; }
}
.notes { font-size: .85rem; color: var(--muted); margin: .25rem 0; }
.notes summary { cursor: pointer; }
.parts h3 { font-size: 1rem; }
.page h2 { font-size: 1.2rem; }