script.js

//Inject CSS code
var div = document.createElement("div");
div.innerHTML = "<div class='overlay'></div>";

//Hide Facebook bar
$('#pageNav').attr('hidden', 'true');

//Modify mouse scrolling event
document.body.appendChild(div);

if (window.addEventListener) window.addEventListener('DOMMouseScroll', wheel, false);
window.onmousewheel = document.onmousewheel = wheel;

function wheel(event) {
 	var delta = 0;
    if (event.wheelDelta) delta = event.wheelDelta / 120;
    else if (event.detail) delta = -event.detail / 3;

    handle(delta);
    if (event.preventDefault) event.preventDefault();
    event.returnValue = false;
}

function handle(delta) {
    var time = 1000;
	var distance = 50;
    
    $('html, body').stop().animate({
        scrollTop: $(window).scrollTop() - (distance * delta)
    }, time );
}