html, body {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  background: #292a33;
  overflow: hidden;
}

function setup() {
  createCanvas(windowWidth, windowHeight);
  noStroke();

  for (let x = 0; x < width; x++) {
    fill(map(x, 0, width, 255, 0), 0, 0);
    rect(x, 0, 1, height);
  }
}