body {
  font-family: system-ui;
  background: linear-gradient(#9198e5,#e66465);
  color: white;
  height: 100vh;
  margin: 0;
  display: grid;
  /*place-items: center;*/
  font-size: calc(100% + 1vw + 1vh);
}

h1 {
  font-size: calc(100% + 1vw + 1vh);
}

.btn-group-lg>.btn, .btn-lg {
  font-size: calc(70% + 1vw + 1vh);
  border-radius: 0.6rem;
}

#demo {
    display: none;
}