html,
body {
  margin: 0;
  min-height: 100%;
  background: #071622;
  color: #f8d36a;
  font-family: Arial, sans-serif;
}

body {
  display: grid;
  min-height: 100vh;
  min-height: 100dvh;
  place-items: center;
}

.box {
  padding: 24px;
  text-align: center;
  font-size: 16px;
  line-height: 1.8;
}

.btn {
  display: inline-block;
  margin-top: 12px;
  padding: 8px 18px;
  border-radius: 6px;
  background: #f8c53a;
  color: #111;
  font-weight: 700;
  text-decoration: none;
}

.btn[hidden] {
  display: none;
}