Changing call to .css('width') to .width()

Per the jQuery docs (http://api.jquery.com/width/):

        The difference between .css(width) and .width() is that the latter returns a
        unit-less pixel value (for example, 400) while the former returns a value with
        units intact (for example, 400px). The .width() method is recommended when an
        element's width needs to be used in a mathematical calculation.
Merge pull request #73 from noah/master

Changing call to .css('width') to .width()