:root {
  --bg: #0f1115;
  --card: #171a21;
  --line: #262b36;
  --fg: #e8eaf0;
  --dim: #9aa3b2;
  --accent: #4c8dff;
  --good: #2ea36b;
  --bad: #d9534f;
}
* { box-sizing: border-box; -webkit-tap-highlight-color: transparent; }
html, body { margin: 0; padding: 0; }
body {
  overflow-x: hidden;
  background: var(--bg);
  color: var(--fg);
  font: 16px/1.5 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  padding: 0 0 40px;
}
header {
  padding: 18px 16px 12px;
  border-bottom: 1px solid var(--line);
  position: sticky; top: 0; background: var(--bg); z-index: 5;
}
h1 { font-size: 19px; margin: 0; letter-spacing: .2px; }
h2 { font-size: 14px; text-transform: uppercase; letter-spacing: .8px; color: var(--dim); margin: 22px 0 10px; }
.sub { color: var(--dim); font-size: 13px; margin-top: 4px; }
main { max-width: 780px; margin: 0 auto; padding: 0 12px; width: 100%; }
.card { min-width: 0; overflow-wrap: anywhere; background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 16px; margin-top: 14px; }
.hidden { display: none; }
footer { max-width: 780px; margin: 22px auto 0; padding: 0 16px; font-size: 12px; }

/* buttons */
.btn {
  background: #222735; color: var(--fg); border: 1px solid var(--line);
  border-radius: 10px; padding: 11px 16px; font-size: 15px; cursor: pointer;
  font-family: inherit;
}
.btn:active { transform: translateY(1px); }
.btn:disabled { opacity: .4; cursor: default; }
.btn.ghost { background: transparent; }
.btn.small { padding: 7px 12px; font-size: 13px; }
.btn.active { border-color: var(--accent); background: #1d2942; color: #cfe0ff; }

.sizes { display: flex; gap: 8px; flex-wrap: wrap; }
.btn.size { min-width: 64px; }
.customrow { display: flex; gap: 8px; align-items: center; margin-top: 10px; font-size: 14px; color: var(--dim); }
.customrow input {
  width: 90px; background: #0f131b; border: 1px solid var(--line); color: var(--fg);
  border-radius: 8px; padding: 9px 10px; font: inherit;
}

.groups { display: grid; grid-template-columns: repeat(auto-fill, minmax(60px, 1fr)); gap: 8px; margin-top: 10px; }
.btn.group { display: flex; flex-direction: column; align-items: center; gap: 2px; padding: 9px 4px; }
.gnum { font-size: 15px; }
.gbest { font-size: 11px; color: var(--bad); }
.gbest.pass { color: var(--good); }

/* quiz */
.quizbar { display: flex; align-items: center; justify-content: space-between; gap: 10px; margin-bottom: 12px; }
.progress { font-size: 13px; color: var(--dim); }
.meta { font-size: 12px; color: var(--dim); margin-bottom: 8px; }
.qtext { font-size: 16px; white-space: pre-wrap; margin-bottom: 14px; }
.choices { display: flex; flex-direction: column; gap: 8px; }
.choice {
  display: flex; gap: 10px; align-items: flex-start; text-align: left;
  background: #1b1f29; border: 1px solid var(--line); color: var(--fg);
  border-radius: 10px; padding: 11px 12px; cursor: pointer; font: inherit; width: 100%;
}
.choice.picked { border-color: var(--accent); background: #1d2942; }
.letter {
  flex: 0 0 22px; font-weight: 700; color: var(--accent);
}
.ctext { flex: 1; min-width: 0; overflow-wrap: anywhere; }
.navrow { display: flex; gap: 8px; margin-top: 16px; }
.navrow .btn { flex: 1; }

/* results */
.score { display: flex; align-items: baseline; gap: 12px; margin: 6px 0 2px; }
.big { font-size: 32px; font-weight: 700; }
.big.pass { color: var(--good); }
.big.fail { color: var(--bad); }
.pct { font-size: 18px; color: var(--dim); }

.rev { border-top: 1px solid var(--line); padding: 14px 0; }
.revmeta { font-size: 12px; color: var(--dim); margin-bottom: 6px; }
.revq { white-space: pre-wrap; margin-bottom: 10px; }
.revrow { display: flex; gap: 10px; align-items: flex-start; padding: 9px 10px; border-radius: 8px; margin-bottom: 6px; font-size: 15px; }
.revrow.right { background: rgba(46,163,107,.13); border: 1px solid rgba(46,163,107,.45); }
.revrow.wrong { background: rgba(217,83,79,.11); border: 1px solid rgba(217,83,79,.4); }
.revrow .tag { flex: 0 0 auto; font-size: 11px; color: var(--dim); text-transform: uppercase; letter-spacing: .5px; }
.revnote { font-size: 12px; color: var(--dim); font-style: italic; margin-top: 4px; }

@media (max-width: 480px) {
  .revrow .tag { display: none; }
  .navrow { position: sticky; bottom: 0; background: var(--card); padding-top: 10px; }
}