:root {
  --blue: #253069;
  --red: #be1e32;
  --dark: #231f20;
  --bg: #f5f6fa;
  --ok: #1e7a3c;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body {
  font-family: "Gilroy", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--dark);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}
header {
  background: var(--blue);
  color: #fff;
  padding: 18px 24px 0;
}
header .brand {
  color: #fff;
  opacity: .7;
  font-size: 13px;
  text-decoration: none;
}
header h1 { font-size: 24px; margin: 6px 0 14px; }
header nav { display: flex; gap: 4px; }
header nav a {
  color: #fff;
  text-decoration: none;
  padding: 10px 18px;
  font-size: 14px;
  font-weight: 700;
  border-radius: 8px 8px 0 0;
  opacity: .75;
}
header nav a.active { background: var(--bg); color: var(--blue); opacity: 1; }

main { flex: 1; max-width: 860px; width: 100%; margin: 0 auto; padding: 24px; }
footer { text-align: center; padding: 16px; font-size: 12px; color: #888; }
footer a { color: var(--blue); }

.loading { text-align: center; color: #888; padding: 60px 0; }
.card {
  background: #fff;
  border-radius: 12px;
  padding: 22px;
  box-shadow: 0 2px 10px rgba(35,31,32,.08);
  margin-bottom: 18px;
}
h2 { color: var(--blue); font-size: 20px; margin-bottom: 12px; }
h3 { color: var(--blue); font-size: 16px; margin: 14px 0 8px; }
.muted { color: #777; font-size: 13px; }

/* filters */
.filter-group { margin: 12px 0; }
.filter-group .label { font-size: 12px; font-weight: 700; text-transform: uppercase; letter-spacing: 1px; color: #999; margin-bottom: 6px; }
.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  border: 1.5px solid #ccc;
  background: #fff;
  border-radius: 999px;
  padding: 6px 14px;
  font-size: 13px;
  cursor: pointer;
  color: var(--dark);
}
.chip.on { border-color: var(--blue); background: var(--blue); color: #fff; }
.btn {
  display: inline-block;
  background: var(--red);
  color: #fff;
  border: none;
  border-radius: 8px;
  padding: 12px 26px;
  font-size: 15px;
  font-weight: 700;
  cursor: pointer;
  text-decoration: none;
}
.btn.secondary { background: #fff; color: var(--blue); border: 1.5px solid var(--blue); }
.btn:disabled { opacity: .4; cursor: default; }

/* quiz */
.quiz-top { display: flex; justify-content: space-between; align-items: baseline; font-size: 13px; color: #777; margin-bottom: 10px; }
.pace-slow { color: var(--red); font-weight: 700; }
.case-setup {
  background: #eef1fb;
  border-left: 4px solid var(--blue);
  padding: 12px 14px;
  border-radius: 0 8px 8px 0;
  font-size: 14px;
  margin-bottom: 14px;
}
.stem { font-size: 17px; line-height: 1.5; margin-bottom: 16px; }
.opts { display: flex; flex-direction: column; gap: 10px; }
.opt {
  text-align: left;
  background: #fff;
  border: 1.5px solid #ddd;
  border-radius: 10px;
  padding: 12px 14px;
  font-size: 15px;
  cursor: pointer;
  line-height: 1.4;
}
.opt:hover { border-color: var(--blue); }
.opt.correct { border-color: var(--ok); background: #ecf7f0; }
.opt.wrong { border-color: var(--red); background: #fbeeee; }
.opt:disabled { cursor: default; }
.explain {
  margin-top: 16px;
  background: #f6f7f9;
  border-radius: 10px;
  padding: 14px;
  font-size: 14px;
  line-height: 1.55;
}
.explain .ref { display: block; margin-top: 8px; color: #777; font-size: 12px; }
.trap-tag {
  display: inline-block;
  background: var(--blue);
  color: #fff;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 1px;
  text-transform: uppercase;
  border-radius: 999px;
  padding: 3px 10px;
  margin-bottom: 10px;
}

/* results & progress tables */
table { width: 100%; border-collapse: collapse; font-size: 14px; }
th, td { text-align: left; padding: 8px 10px; border-bottom: 1px solid #eee; }
th { font-size: 12px; text-transform: uppercase; letter-spacing: 1px; color: #999; }
.bar { background: #eee; border-radius: 999px; height: 8px; overflow: hidden; min-width: 80px; }
.bar > div { height: 100%; background: var(--blue); }
.score-big { font-size: 42px; font-weight: 800; color: var(--blue); }

/* topics */
.topic-row { display: flex; justify-content: space-between; align-items: center; gap: 12px; padding: 14px 0; border-bottom: 1px solid #eee; }
.topic-row:last-child { border-bottom: none; }
.topic-row .t-title { font-weight: 700; color: var(--blue); }
.status-pill { font-size: 11px; font-weight: 700; border-radius: 999px; padding: 3px 10px; background: #eee; color: #777; }
.status-pill.verified { background: #ecf7f0; color: var(--ok); }

/* notes rendering */
.notes { line-height: 1.6; font-size: 15px; }
.notes h1, .notes h2, .notes h3 { color: var(--blue); margin: 18px 0 8px; }
.notes ul, .notes ol { margin: 8px 0 8px 22px; }
.notes table { margin: 10px 0; }
.notes code { background: #f0f1f5; padding: 1px 5px; border-radius: 4px; font-size: 13px; }
.notes img, .visual img { max-width: 100%; }

/* flashcards */
.fc {
  background: #fff;
  border: 2px solid var(--blue);
  border-radius: 14px;
  min-height: 180px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 24px;
  font-size: 18px;
  cursor: pointer;
  user-select: none;
}
.fc.back { background: var(--blue); color: #fff; }
.fc-nav { display: flex; justify-content: center; gap: 12px; margin-top: 14px; align-items: center; }

@media (max-width: 600px) {
  main { padding: 14px; }
  header nav a { padding: 10px 12px; }
}