:root {
  --bg: #f4f6fb;
  --card: #ffffff;
  --ink: #1a2233;
  --muted: #667085;
  --line: #e3e8f0;
  --brand: #2f5fe0;
  --brand-ink: #ffffff;
  --good: #1f9d55;
  --good-bg: #e7f6ec;
  --bad: #d64545;
  --bad-bg: #fbeaea;
  --warn: #b7791f;
  --shadow: 0 1px 3px rgba(16,24,40,.08), 0 1px 2px rgba(16,24,40,.04);
  --radius: 14px;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg);
  color: var(--ink);
  font: 16px/1.5 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.topbar {
  display: flex; align-items: center; justify-content: space-between;
  padding: 14px 20px;
  background: var(--card);
  border-bottom: 1px solid var(--line);
  position: sticky; top: 0; z-index: 10;
}
.brand { font-weight: 800; letter-spacing: .2px; color: var(--brand); }
.nav { display: flex; gap: 6px; flex-wrap: wrap; }
.nav button {
  border: 1px solid var(--line); background: var(--card); color: var(--muted);
  padding: 6px 12px; border-radius: 999px; cursor: pointer; font-size: 14px;
}
.nav button.active { background: var(--brand); color: var(--brand-ink); border-color: var(--brand); }
.nav button:disabled { opacity: .45; cursor: not-allowed; }

.app { flex: 1; width: 100%; max-width: 780px; margin: 0 auto; padding: 24px 18px 48px; }

.card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  box-shadow: var(--shadow); padding: 22px; margin-bottom: 18px;
}
h1 { font-size: 24px; margin: 0 0 6px; }
h2 { font-size: 19px; margin: 0 0 12px; }
.lead { color: var(--muted); margin-top: 0; }

label { display: block; font-weight: 600; margin: 14px 0 4px; font-size: 14px; }
.hint { font-weight: 400; color: var(--muted); font-size: 13px; }
input[type=number], input[type=date], select {
  width: 100%; padding: 10px 12px; border: 1px solid var(--line); border-radius: 10px;
  font-size: 16px; background: #fff; color: var(--ink);
}
.row { display: flex; gap: 14px; }
.row > div { flex: 1; }

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  background: var(--brand); color: var(--brand-ink); border: none;
  padding: 12px 20px; border-radius: 12px; font-size: 16px; font-weight: 700;
  cursor: pointer; margin-top: 18px;
}
.btn.secondary { background: #eef1f8; color: var(--ink); }
.btn.ghost { background: transparent; color: var(--brand); border: 1px solid var(--line); }
.btn:disabled { opacity: .5; cursor: not-allowed; }
.btn.block { width: 100%; }

.progress-line { height: 8px; background: var(--line); border-radius: 999px; overflow: hidden; margin: 6px 0 2px; }
.progress-line > div { height: 100%; background: var(--brand); transition: width .25s; }

.qmeta { display: flex; justify-content: space-between; align-items: center; color: var(--muted); font-size: 13px; margin-bottom: 8px; }
.timer { font-variant-numeric: tabular-nums; font-weight: 700; }
.timer.slow { color: var(--bad); }
.tag-pill { background: #eef1f8; color: var(--brand); padding: 2px 9px; border-radius: 999px; font-weight: 700; font-size: 12px; }

.stem { font-size: 19px; margin: 6px 0 18px; }
.choices { display: grid; gap: 10px; }
.choice {
  text-align: left; border: 1.5px solid var(--line); background: #fff; color: var(--ink);
  padding: 13px 15px; border-radius: 12px; cursor: pointer; font-size: 17px;
  display: flex; gap: 12px; align-items: baseline;
}
.choice:hover { border-color: #c3ccdd; }
.choice .key { font-weight: 800; color: var(--muted); }
.choice.selected { border-color: var(--brand); }
.choice.correct { border-color: var(--good); background: var(--good-bg); }
.choice.wrong { border-color: var(--bad); background: var(--bad-bg); }
.choice:disabled { cursor: default; }

.feedback { margin-top: 16px; border-radius: 12px; padding: 14px 16px; }
.feedback.correct { background: var(--good-bg); }
.feedback.wrong { background: var(--bad-bg); }
.feedback h3 { margin: 0 0 6px; font-size: 15px; }
.fast { border-left: 3px solid var(--brand); padding-left: 12px; margin: 10px 0; }
.fast .fast-label { font-size: 12px; font-weight: 800; color: var(--brand); text-transform: uppercase; letter-spacing: .4px; }
details.worked { margin-top: 8px; }
details.worked summary { cursor: pointer; color: var(--brand); font-weight: 600; }
details.worked p { color: var(--ink); }

sup { font-size: .72em; }

.masterygrid { display: grid; gap: 10px; }
.masteryrow { display: grid; grid-template-columns: 1fr auto; align-items: center; gap: 10px;
  border: 1px solid var(--line); border-radius: 12px; padding: 10px 14px; }
.masteryrow .name { font-weight: 600; }
.masteryrow .sub { color: var(--muted); font-size: 13px; }
.badge { padding: 3px 10px; border-radius: 999px; font-size: 12px; font-weight: 800; }
.badge.weak { background: var(--bad-bg); color: var(--bad); }
.badge.developing { background: #fdf3e2; color: var(--warn); }
.badge.solid { background: var(--good-bg); color: var(--good); }
.badge.slow { background: #eef1f8; color: var(--brand); margin-left: 6px; }

.scorebig { font-size: 52px; font-weight: 800; color: var(--brand); line-height: 1; }
.scorewrap { display: flex; align-items: baseline; gap: 14px; }
.trend { margin-top: 8px; }

.empty { color: var(--muted); text-align: center; padding: 30px 10px; }
.kpis { display: flex; gap: 14px; flex-wrap: wrap; margin: 10px 0; }
.kpi { background: #f7f9fe; border: 1px solid var(--line); border-radius: 12px; padding: 10px 16px; flex: 1; min-width: 120px; }
.kpi .n { font-size: 24px; font-weight: 800; }
.kpi .l { color: var(--muted); font-size: 13px; }

.footer { border-top: 1px solid var(--line); background: var(--card); color: var(--muted);
  font-size: 12px; text-align: center; padding: 14px 20px; }
.footer p { max-width: 780px; margin: 0 auto; }

@media (max-width: 520px) {
  .row { flex-direction: column; gap: 0; }
  .scorebig { font-size: 42px; }
}