// When the document loads do everything inside here ...
var totalNum = 4; //the total number of images in a folder.
var rndNum = (Math.floor(Math.random() * totalNum)+1);// added +1 to start count form 1 and not zeo

$(document).ready(function(){
	
$("#fal-logo").css("background","url(http://dev.lib.utexas.edu/fal/images/header/header-" 
+ rndNum  + ".png)  no-repeat 254px 0");
}); //close $(document)