This tutorial explains how you can match the height of several HTML elements when their content does not have the same height.

Open the JavaScript configuration file lib/js/template.js. In there, take a look at the function matchHeights:

matchHeights: function() {
	YOOBase.matchHeight('div.headerbox div.deepest', 20);
	YOOBase.matchHeight('div.topbox div.deepest', 20);
	YOOBase.matchHeight('div.bottombox div.deepest', 20);
	YOOBase.matchHeight('div.maintopbox div.deepest', 20);
	YOOBase.matchHeight('div.mainbottombox div.deepest', 20);
	YOOBase.matchHeight('div.contenttopbox div.deepest', 20);
	YOOBase.matchHeight('div.contentbottombox div.deepest', 20);
}

The "20" at the end means that the minimum height of all DIVs gets set to 20 pixels. You can simply add a line to match your HTML elements. For example:

YOOBase.matchHeight('li.myselector');

Now all li tags with the CSS class "myselector" will be checked for their heights, and the biggest height will be set for all of them.