:root {
  --paper: #f3efe6;
  --card: #fffdf8;
  --ink: #1c1916;
  --muted: #5e584f;
  --line: #e2d9cc;
  --good: #0d6b4d;
  --bad: #9d3412;
  --warn: #8a5a12;
  --mark: #f4e2c4;
  color-scheme: light;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 18px/1.5 Georgia, "Iowan Old Style", Palatino, serif;
}

.sheet {
  width: min(820px, calc(100% - 32px));
  margin: 32px auto 64px;
}

.sheet.narrow { width: min(720px, calc(100% - 32px)); }
.sheet.wide { width: min(1080px, calc(100% - 32px)); }

h2 {
  margin: 8px 0 12px;
  font-size: 26px;
  font-weight: 600;
  letter-spacing: -0.02em;
}

.kicker {
  margin: 0;
  font: 600 12px/1.2 "Avenir Next", "Segoe UI", sans-serif;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
}

h1 {
  margin: 8px 0 12px;
  font-size: 40px;
  font-weight: 600;
  letter-spacing: -0.03em;
  line-height: 1.1;
}

h1.good { color: var(--good); }
h1.bad { color: var(--bad); }

.lead { margin: 0 0 24px; color: var(--muted); }

.stack { display: grid; gap: 18px; }

.fields { display: grid; gap: 12px; grid-template-columns: 1fr 1fr; }
.fields .wide { grid-column: 1 / -1; }

label span, legend {
  display: block;
  margin-bottom: 6px;
  font: 600 13px/1.2 "Avenir Next", "Segoe UI", sans-serif;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--muted);
}

fieldset {
  margin: 0;
  padding: 0;
  border: 0;
}

input[type="text"], input[type="email"], input[type="password"], input:not([type]) {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--card);
  color: var(--ink);
  font: 18px/1.4 Georgia, serif;
}

.cards { display: grid; gap: 12px; }

.card {
  display: grid;
  gap: 2px;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--card);
  cursor: pointer;
}

a.card {
  color: inherit;
  text-decoration: none;
}

a.card:hover { border-color: var(--ink); }

.card:has(input:checked) {
  border-color: var(--good);
  box-shadow: inset 3px 0 0 var(--good);
}

.card input { position: absolute; opacity: 0; }

.card .level, .card .meta, .topic, .note, .pick, .explain {
  font: 14px/1.4 "Avenir Next", "Segoe UI", sans-serif;
  color: var(--muted);
}

.card .code { font-size: 22px; }

.roster-block { margin-top: 28px; }

.switch {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 0 0 22px;
}

.switch a {
  padding: 8px 14px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--card);
  color: inherit;
  text-decoration: none;
  font: 600 14px/1 "Avenir Next", "Segoe UI", sans-serif;
}

.switch a.on {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--paper);
}

pre.cmd {
  margin: 0 0 14px;
  padding: 12px 14px;
  overflow: auto;
  border-radius: 10px;
  background: #1c1916;
  color: #f3efe6;
  font: 14px/1.45 ui-monospace, "SF Mono", Menlo, Consolas, monospace;
}

.lesson p { margin: 0 0 14px; }
.lesson h2 { margin-top: 28px; }
.lesson ul { margin: 0 0 14px; padding-left: 1.2em; }

.roster {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.roster li {
  padding: 8px 14px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--card);
  font: 16px/1.2 "Avenir Next", "Segoe UI", sans-serif;
}

.roster span {
  color: var(--muted);
  font-size: 13px;
}

button {
  justify-self: start;
  padding: 12px 22px;
  border: 0;
  border-radius: 999px;
  background: var(--ink);
  color: var(--paper);
  font: 600 16px/1 "Avenir Next", "Segoe UI", sans-serif;
  cursor: pointer;
}

.banner {
  margin: 0;
  padding: 12px 14px;
  border-radius: 10px;
  background: var(--mark);
  color: var(--warn);
  font: 16px/1.4 "Avenir Next", "Segoe UI", sans-serif;
}

.banner.bad { background: #f8e4dc; color: var(--bad); }
.banner.good { background: #e5f3ec; color: var(--good); }
.banner.warn { background: var(--mark); color: var(--warn); }

.bar {
  position: sticky;
  top: 0;
  z-index: 2;
  display: flex;
  justify-content: space-between;
  gap: 16px;
  align-items: center;
  padding: 12px 20px;
  background: #1c1916;
  color: #f3efe6;
  font: 15px/1.3 "Avenir Next", "Segoe UI", sans-serif;
}

.bar span { display: block; color: #cfc6b8; }

.timer {
  font-variant-numeric: tabular-nums;
  font-size: 22px;
}

.timer.late { color: #f0b429; }

.question {
  padding: 8px 0 18px;
  border-top: 1px solid var(--line);
}

.question header {
  display: flex;
  gap: 10px;
  align-items: baseline;
}

.num {
  font: 600 14px/1 "Avenir Next", "Segoe UI", sans-serif;
  color: var(--good);
}

.choices { display: grid; gap: 8px; }

.choices label {
  display: grid;
  grid-template-columns: auto auto 1fr;
  gap: 10px;
  align-items: start;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--card);
  cursor: pointer;
}

.choices label:has(input:checked) { border-color: var(--ink); }

.letter {
  font: 600 14px/1.4 "Avenir Next", "Segoe UI", sans-serif;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 8px 0 28px;
  font: 16px/1.4 "Avenir Next", "Segoe UI", sans-serif;
}

th, td {
  padding: 8px 8px 8px 0;
  border-bottom: 1px solid var(--line);
  text-align: left;
}

th { color: var(--muted); font-size: 13px; letter-spacing: 0.04em; text-transform: uppercase; }

.review { list-style: none; padding: 0; margin: 0 0 8px; display: grid; gap: 6px; }

.review li {
  padding: 8px 10px;
  border-radius: 8px;
  background: transparent;
}

.review .is-correct { background: #e5f3ec; }
.review .is-chosen:not(.is-correct) { background: #f8e4dc; }

.review em {
  margin-left: 8px;
  font: 12px/1 "Avenir Next", "Segoe UI", sans-serif;
  font-style: normal;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.question.miss { border-top-color: #e7c2b6; }
a { color: var(--good); }

.sub {
  display: block;
  color: var(--muted);
  font: 13px/1.3 "Avenir Next", "Segoe UI", sans-serif;
}

.tight { font: 14px/1.4 "Avenir Next", "Segoe UI", sans-serif; }

.good-text { color: var(--good); }
.bad-text { color: var(--bad); }

.split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

.chip {
  display: inline-block;
  margin: 0 4px 4px 0;
  padding: 2px 8px;
  border-radius: 999px;
  background: var(--line);
  font: 12px/1.5 "Avenir Next", "Segoe UI", sans-serif;
}

.chip.good { background: #e5f3ec; color: var(--good); }
.chip.bad { background: #f8e4dc; color: var(--bad); }

.topics {
  list-style: none;
  margin: 0;
  padding: 0;
}

.topics li {
  padding: 8px 0;
  border-bottom: 1px solid var(--line);
  font: 16px/1.4 "Avenir Next", "Segoe UI", sans-serif;
}

.topics span { color: var(--muted); }

@media (max-width: 640px) {
  h1 { font-size: 32px; }
  .fields, .split { grid-template-columns: 1fr; }
  .bar { align-items: flex-start; }
}