:root { color-scheme: light dark; }
body{
  margin:0; min-height:100vh; display:grid; place-items:center;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
}
.card{
  padding: 28px 22px; border-radius: 16px; max-width: 520px; width: min(92vw, 520px);
  border: 1px solid rgba(127,127,127,.25);
  box-shadow: 0 10px 30px rgba(0,0,0,.12);
  text-align:center;
}
h1{ margin: 0 0 10px; font-size: clamp(28px, 4vw, 44px); }
p{ margin: 10px 0; opacity: .85; }
button{
  margin-top: 12px; padding: 10px 14px; border-radius: 12px;
  border: 1px solid rgba(127,127,127,.35); background: transparent;
  cursor: pointer;
}
button:hover{ transform: translateY(-1px); }
#msg{ margin-top: 12px; font-weight: 600; }