Sub-menu problem

Hi there,
I have a problem with the sub-menu. In my menu I have 6 pages,each page have sub-pages. My problem is that one of my pages from the menu, it is compuse from 2 words. In that page,my second color in the sub-menu that appears when you select the page is not cover all.
To understand better what I am talking about,my page is: http://ceydemadrid.org/ and in Mesajes Mediumnicos it is a sub-menu,if you open it the sub-menu,you will see that the blue color doesn´t cover all. I do want that that sub-menu looks like the other ones.
How can I fix that?
Than you for your help.