body {
  background-color: #131313;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: sans-serif;
}

body,
html {
  height: 100%;
  width: 100%;
  margin: 0;
  padding: 0;
  overflow: hidden;
}

#demo {
  height: 350px;
  display: flex;
  align-items: center;
  justify-content: center;
}

h1 {
  color: white;
  font-size: 60px;
  font-weight: 400;
}

@media only screen and (max-width: 540px) {
  h1 {
    font-size: 40px;
  }
}