Integrate justified menus

I am looking to implement: http://www.barrelny.com/blog/text-align-justify-and-rwd/

Specifically

#Grid:after{
    content: '';
    display: inline-block;
    width: 100%;
}

The code I am attempting to use is below.

.nice-menu {
	text-align: justify;
}
.nice-menu:after {
	content: '';
	display: inline-block;
	width: 100%;
}

The after element is being placed as expected but the content and display rules are being overridden.