canvas = document.querySelector('canvas');
    const ctx = canvas.getContext('2d');

    let WIDTH = document.documentElement.clientWidth;
    let HEIGHT = document.documentElement.clientHeight;

    canvas.width = WIDTH;
    canvas.height = HEIGHT;

    function random(number) {
      return Math.floor(Math.random()*number);
    }

    function draw() {
      ctx.clearRect(0,0,WIDTH,HEIGHT);
      for(let i = 0; i < 100; i++) {
        ctx.beginPath();
        ctx.fillStyle = 'rgba(255,0,0,0.5)';
        c