<!-- https://css-doodle.com -->

<css-doodle>
  :doodle {
    @size: 100vmax;
    background-blend-mode: difference; 
    filter: hue-rotate(-60deg);
    background: @multi(100, (
      linear-gradient(
        @r(360deg),
        @multi(10, @pick(blue, #fff))
      ),
      radial-gradient(
        @multi(10, @pick(blue, #fff))
      )
    ));
  }
</css-doodle>
html, body {
  margin: 0;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

body:after {
  content: 'Click to update';
  position: absolute;
  font-size: .9em;
  color: rgba(255, 255, 255, .5); 
  bottom: 1em;
  font-family: Helvetica;
}
document.body.addEventListener('click', function(e) {
  e.target.update && e.target.update();
})

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/css-doodle/0.4.1/css-doodle.min.js