:root {
  color-scheme: light;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Noto Sans TC", sans-serif;
  background: #f5f7fb;
  color: #16213b;
}

* { box-sizing: border-box; }
body { margin: 0; min-height: 100vh; }
button, input { font: inherit; }
.shell { width: min(760px, 100%); margin: 0 auto; padding: 24px 16px 48px; }
.card { background: #fff; border-radius: 20px; box-shadow: 0 10px 28px rgba(33, 55, 105, .12); padding: 24px; }
.eyebrow { color: #50627f; font-weight: 700; margin: 0 0 8px; }
h1, h2 { line-height: 1.35; }
.subject-grid, .actions { display: grid; gap: 12px; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); }
.primary, .secondary, .choice {
  border: 0;
  border-radius: 14px;
  cursor: pointer;
  min-height: 52px;
  padding: 12px 18px;
}
.primary { background: #3157d5; color: white; font-weight: 800; }
.secondary { background: #edf1fc; color: #1e3d99; font-weight: 700; }
.choice { display: block; width: 100%; margin: 10px 0; text-align: left; background: #f2f5fb; color: #16213b; }
.choice[aria-pressed="true"] { outline: 3px solid #3157d5; background: #e8edff; }
.confidence { display: flex; gap: 10px; align-items: center; margin: 20px 0; }
.progress { height: 10px; border-radius: 999px; background: #e5e9f3; overflow: hidden; }
.progress > span { display: block; height: 100%; background: #3157d5; }
.reading-stimulus { margin: 0 0 1rem; padding: 1rem; border-radius: .75rem; background: #f5f1e8; color: #2d2a25; line-height: 1.75; }
.reading-stimulus h2 { margin: 0 0 .5rem; font-size: 1rem; }
.reading-stimulus p { margin: 0; white-space: pre-wrap; }
.review { border-top: 1px solid #dde3ef; padding: 16px 0; }
.review summary { cursor: pointer; font-weight: 800; }
.status { color: #50627f; font-size: .92rem; }
.loading-primary { font-size: 1.1rem; font-weight: 700; line-height: 1.5; margin: 0 0 10px; color: #16213b; }
.loading-secondary { color: #50627f; font-size: .92rem; margin: 0; }
.error { color: #8b1e26; }
@media (max-width: 520px) {
  .shell { padding: 12px 10px 32px; }
  .card { padding: 18px; border-radius: 14px; }
}