html, body {
  margin: 0;
  padding: 0;
  text-align: center;
  background-color: yellow;
  color: black;
  font-size: x-large;
  
}
canvas {
  display: block;
  
}
.warning-background {
  background: repeating-linear-gradient(
    -45deg, /* Slanted angle */
    black 0px,
    black 80px,  /* Thickness of black stripe */
    yellow 80px,
    yellow 160px  /* Thickness of yellow stripe */
  );
}