Background Changing and Button Color Fix

[xsoder]

I added a background changing java script function and a rounded button with gradient.

function randomColor() {
  const hexnum = '0123456789ABCDEF';
  let color = '#';
  for (var i = 0; i < 6; i++) {
    color += hexnum[Math.floor(Math.random() * 16)];
  }
  return color;
}