:root {
  color-scheme: light dark;
  --bg: #ffffff;
  --fg: #1d1d1f;
  --muted: #5b5b66;
  --line: #d4d4dc;
  --accent: #1f5fbf;
  --warn-bg: #fff4d6;
  --warn-fg: #6b4a00;
  --bad: #a3261b;
  --good: #1d6b35;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #17171a;
    --fg: #ececf1;
    --muted: #a6a6b3;
    --line: #3a3a44;
    --accent: #7aa9f0;
    --warn-bg: #3a2f10;
    --warn-fg: #f5d68a;
    --bad: #ff8a80;
    --good: #7fd69a;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0 auto;
  max-width: 52rem;
  padding: 1rem;
  background: var(--bg);
  color: var(--fg);
  font: 16px/1.5 system-ui, -apple-system, "Segoe UI", sans-serif;
}
h1 { font-size: 1.5rem; margin: 0.5rem 0; }
h2 { font-size: 1.25rem; }
h3 { font-size: 1.05rem; }
nav { display: flex; gap: 0.5rem; margin: 0.5rem 0; }
button {
  font: inherit;
  padding: 0.4rem 0.9rem;
  border: 1px solid var(--accent);
  border-radius: 0.4rem;
  background: var(--accent);
  color: var(--bg);
  cursor: pointer;
}
button.secondary, nav button[aria-pressed="false"] { background: transparent; color: var(--accent); }
button:disabled { opacity: 0.5; cursor: not-allowed; }
input[type="text"] { font: inherit; padding: 0.3rem 0.5rem; border: 1px solid var(--line); border-radius: 0.3rem; background: var(--bg); color: var(--fg); }
.banner { background: var(--warn-bg); color: var(--warn-fg); padding: 0.5rem 0.75rem; border-radius: 0.4rem; }
.muted { color: var(--muted); }
.message:empty { display: none; }
.message { color: var(--bad); font-weight: 600; }
#save-message { color: var(--good); }
.actions { display: flex; flex-wrap: wrap; gap: 0.5rem; align-items: center; }
.questions { padding-left: 0; list-style: none; }
.questions fieldset { border: 1px solid var(--line); border-radius: 0.4rem; margin: 0 0 0.75rem; padding: 0.5rem 0.75rem; }
.questions legend { font-weight: 600; padding: 0 0.25rem; }
.questions .topic { display: block; font-weight: 400; font-size: 0.85rem; color: var(--muted); }
.questions label { display: block; padding: 0.15rem 0; }
table { border-collapse: collapse; width: 100%; margin: 0.5rem 0; }
th, td { text-align: left; padding: 0.35rem 0.5rem; border-bottom: 1px solid var(--line); vertical-align: top; }
.reteach { color: var(--bad); font-weight: 700; }
.badge { font-size: 0.8rem; font-weight: 700; color: var(--bad); margin-left: 0.4rem; }
#missed ol { margin-top: 0.25rem; }