traktor2 on "[Theme: MesoColumn] Remove hover effect in top-navigation"

Hi.

Is it possible to remove the hover effect in the top navigation bar? The site is http://www.lsj-akademie.de/?page_id=69 - I only want to have an underline-effect there (Angebote/Anmeldung), without changing of the background color.

I changed it like that:

#top-navigation .sf-menu a:hover {
   color: #fff;
   text-decoration: underline;
}

But it's not possible to change the background-color there, all my trials had no effect.

Second question: Is it possible to make the main menue to be flush with the sub-menue, so that they both have the same width? Don't know where to change that.

Thanks in advance,
René