: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;
  background: #0d1117;
}
.card{
  padding: 32px 26px; border-radius: 18px; max-width: 520px;
  border: 1px solid rgba(255,255,255,.1);
  box-shadow: 0 10px 40px rgba(0,0,0,.4);
  text-align:center;
}
h1{ font-size: 38px; margin-bottom: 12px; }
p{ opacity: .8; }
button{
  margin-top: 14px; padding: 10px 16px;
  border-radius: 12px; border: 1px solid rgba(255,255,255,.2);
  background: transparent; color: white; cursor: pointer;
}
button:hover{ transform: translateY(-2px); }
#msg{ margin-top: 14px; font-weight: 600; }