Want To Add A Hidden Feature In Your Webpage For Users to Discover? Do This:
Rainbow Webpage
var i = 0; // Define varible "i"
setInterval(function(){
document.body.style.filter = `hue-rotate(${i}deg)`; // Set Hue Of Page To i
if(i == 360){
i = 0; // Set i to 0
} else{
i = i + 2; // Change i by 2
}
}, 60);
enjoy!