:root{--bg:#f7fafc;--card:#ffffff;--accent:#1f6feb;--muted:#6b7280}
*{box-sizing:border-box;font-family:Inter, 'Segoe UI', Tahoma, sans-serif}
body{margin:0;background:linear-gradient(180deg,#f8fbff,#ffffff);color:#0f172a}
.center-card{max-width:640px;margin:6vh auto;padding:28px;background:var(--card);border-radius:14px;box-shadow:0 8px 30px rgba(2,6,23,0.08);text-align:center}
.title{font-size:24px;margin:0 0 8px;color:var(--accent)}
.subtitle{color:var(--muted);margin-bottom:18px}
.field{display:block;text-align:right;margin:8px 0}
.field input{width:100%;padding:10px;border-radius:8px;border:1px solid #e6eef8}
.actions{margin-top:12px;display:flex;gap:10px;justify-content:center}
.btn{padding:10px 18px;border-radius:8px;border:1px solid rgba(2,6,23,0.06);background:#fff;cursor:pointer}
.btn.primary{background:var(--accent);color:#fff;border:none}
.msg{color:#dc2626;margin-top:10px}
.footer{color:var(--muted);font-size:13px;margin-top:18px}

/* exam styles */
.exam-card{max-width:900px;margin:4vh auto;padding:22px;background:var(--card);border-radius:12px;box-shadow:0 8px 40px rgba(2,6,23,0.06)}
.exam-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:10px}
.timer{font-family:monospace;background:#eef6ff;padding:8px 12px;border-radius:8px;color:var(--accent);font-weight:700}
.muted{color:var(--muted)}
.q-card{padding:18px;border-radius:10px;border:1px solid #f0f6ff}
.q-text{font-size:18px;margin:12px 0}
.choices{display:grid;grid-template-columns:1fr 1fr;gap:10px}
.choice{padding:12px;border-radius:10px;border:1px solid #e6eef8;background:#fff;text-align:right;cursor:pointer}
.choice:hover{background:#f8fbff}
.result-card{padding:18px;text-align:center}
.result-card .big{font-size:22px;font-weight:700;margin-top:8px}
.result-card .small{color:var(--muted);margin-top:6px}
.center-msg{padding:28px;text-align:center;color:var(--muted)}
.controls{margin-top:14px;display:flex;align-items:center}