color = 0 function colorRotate(){ color += 10 color = color%360 document.getElementsByClassName('screen-content')[0].style.filter = "sepia(94%) hue-rotate("+color+"deg) saturate(7) brightness(100%)" } if( Math.random() > 0.5){ if( Math.random() > 0.9){ setInterval(colorRotate, 50); } else { document.getElementsByClassName('screen-content')[0].style.filter = "sepia(94%) hue-rotate("+Math.floor(Math.random()*360)+"deg) saturate(7) brightness(100%)" } }