html, body {
  display: block;
  width: 100%;
  height: 100%;
  margin: 0;
  padding: 0;
  font-family: Helvetica, sans-serif;
  background: #fff;
  color: #000;
}

[data-palette] {
  transition: background 1s, color 2s;
}

[data-palette="1"] {
  background: #fff;
  color: #000;
}

[data-palette="2"] {
  background: #9C27B0;
  color: #FFEB3B;
}

[data-palette="3"] {
  background: #9E9E9E;
  color: #E91E63
}