Blink

by OwenMelbz

CSS

body {
    background-image: url('http://attachments.techguy.org/attachments/66283d1129995795/desktop-screenshot-windows-installer-bootup.jpg');
    background-size:100% auto;
    background-repeat:no-repeat;
    margin:0;
    padding:0;
}

JavaScript

if (!($ = window.jQuery)) { // typeof jQuery=='undefined' works too
	script = document.createElement( 'script' );
   script.src = '//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js'; 
	script.onload=Blink;
	document.body.appendChild(script);
} 
else {
	Blink();
}

function Blink() {
	    jQuery('body').append('<div class="b1" style="position:absolute;width:100%;height:50%;background:black;top:0;left:0;"></div>');
    jQuery('body').append('<div class="b2" style="position:absolute;width:100%;height:50%;background:black;bottom:0;left:0;"></div>');
    var b1 =  ($(window).height()/2)*-1;
    jQuery('.b1').css('top', b1);
    var b2 =  ($(window).height()/2)*-1;
    jQuery('.b2').css('bottom', b1);
    var blink = setInterval(function(){
        jQuery('.b1').animate({'top':0}, {duration: 100, queue: false, complete: function(){
            jQuery('.b1').animate({'top':b1}, 100);
        }});
        jQuery('.b2').animate({'bottom':0}, {duration: 100, queue: false, complete: function(){
            jQuery('.b2').animate({'bottom':b2}, 100);
        }});
    }, 5000);
}