body { display: flex; align-items: center; justify-content: center; min-height: 100vh; }
.login-dialog {
  background-color: #ebdcc2;
  border: 1px solid #ccc;
  box-shadow: 0 0 15px #999;
  padding: 2em;
  max-width: 24em;
  text-align: center;
}
.login-dialog h1 { color: #c00000; font-size: 1.3em; margin-top: 0; }
.login-dialog input[type="text"], .login-dialog input[type="password"] {
  width: 100%;
  box-sizing: border-box;
  padding: 0.4em;
  margin: 0.8em 0;
  font-size: 1em;
}
.login-dialog button {
  padding: 0.4em 1.5em;
  font-size: 1em;
  cursor: pointer;
}
.login-error { color: #c00000; font-weight: bold; }