:root {
  --bg: #f6f8fb;
  --card: #ffffff;
  --accent: #2b6ef6;
  --muted: #6b7280;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: Inter, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;
  background: var(--bg);
  color: #111827;
}
.topbar {
  display:flex;
  justify-content:space-between;
  align-items:center;
  padding:12px 20px;
  background: white;
  border-bottom: 1px solid #e6e9ef;
  position: sticky;
  top: 0;
  z-index: 10;
}
.brand { font-weight:700; }
.right { display:flex; gap:12px; align-items:center; }
.coins {
  background: linear-gradient(180deg,#ffd86b,#ffbd00);
  padding:6px 10px;
  border-radius:8px;
  font-weight:700;
}
.container { max-width:820px; margin:36px auto; padding:0 16px; }
.card {
  background: var(--card);
  border-radius:12px;
  padding:18px;
  box-shadow: 0 6px 18px rgba(18,38,63,0.06);
  margin-bottom:16px;
}
.hidden { display:none; }
.question-header { margin-bottom:12px; }
.question-text { font-size:1.1rem; font-weight:600; }
.options { display:flex; flex-direction:column; gap:8px; margin-bottom:12px; }
.option-btn {
  padding:10px 12px;
  border-radius:8px;
  border:1px solid #e6e9ef;
  background: white;
  cursor:pointer;
  text-align:left;
}
.option-btn:hover { border-color:var(--accent); }
.controls { display:flex; gap:8px; align-items:center; margin-bottom:10px; }
#answerInput { flex:1; padding:10px; border-radius:8px; border:1px solid #e6e9ef; }
button { cursor:pointer; padding:10px 12px; border-radius:8px; border:none; background:var(--accent); color:white; }
button.secondary { background:#e6e9ef; color:#111827; }
.hint-box { margin-top:8px; color:#0b61d6; font-style:italic; }
.msg-box { margin-top:10px; color:#b91c1c; font-weight:600; }
.user-info button { background:#fff; color:var(--accent); border:1px solid #e6e9ef; padding:8px 10px; border-radius:8px; }
.footer { text-align:center; color:var(--muted); padding:20px 0; }