:root{
  --bg:#f7f9fc;
  --card:#fff;
  --accent:#0b6ef6;
  --muted:#666;
}
*{box-sizing:border-box}
body{
  margin:0;
  font-family:system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial;
  background:var(--bg);
  color:#111;
}
.container{
  max-width:900px;
  margin:36px auto;
  padding:18px;
}
h1{margin:0 0 12px;font-size:1.6rem}
.card{
  background:var(--card);
  border-radius:10px;
  padding:16px;
  box-shadow:0 6px 18px rgba(28,33,41,0.06);
  margin-bottom:16px;
}
.file-row{display:flex;gap:12px;align-items:center}
.file-row input[type=file]{flex:1}
.controls{display:flex;gap:12px;flex-wrap:wrap;margin-top:12px;align-items:center}
.controls label{font-size:0.95rem}
.actions{margin-top:12px;display:flex;gap:10px}
.btn{
  border:1px solid #ddd;
  background:#fff;
  padding:8px 12px;
  border-radius:8px;
  cursor:pointer;
}
.btn.primary{
  background:var(--accent);
  color:#fff;
  border-color:transparent;
}
.btn:disabled{opacity:0.5;cursor:not-allowed}
.messages{margin-top:10px;color:var(--muted)}
.preview h2{margin-top:0}
.preview .question{
  padding:10px;border-radius:8px;border:1px solid #eee;margin-bottom:8px;
}
.q-header{display:flex;justify-content:space-between;align-items:center}
.options{margin-top:6px;display:flex;flex-direction:column;gap:6px}
.option{
  padding:6px 8px;border-radius:6px;border:1px solid #f0f0f0;
  cursor:pointer;
}
.option.correct{background: #e4f0ff;border-color:#cfe4ff}
.note{font-size:0.9rem;color:var(--muted);margin-top:8px}
footer{margin-top:16px;text-align:center;color:var(--muted)}