body.dark {
  margin:0;
  height:100vh;
  background:linear-gradient(135deg,#020617,#0f172a);
  font-family:Arial,sans-serif;
  color:white;
}
.login-box {
  width:360px;
  margin:15vh auto;
  padding:40px;
  background:#020617;
  border-radius:14px;
  text-align:center;
}
input,button {
  width:100%;
  padding:12px;
  margin-top:10px;
}