horizontal menu nested list problem

I just added

width:auto;

to

#access ul ul a {}

and it is a step further in the right direction!

However, the backgrounds of the sub menu list items still don’t line up!

I have only tested this is Firefox 26.0 and it works! Remember, I am using a child theme of Twenty Ten. I simply added the following to my editor style.css:

#access ul ul {
	width: auto;
}

#access ul ul li {
	width:100%;
}

#access ul ul a {
	white-space: nowrap;
	width:auto;
}