Menu Underline Spacious Pro Theme

Hello, I have been looking through the forums here for a little help. I would like to have the menu item underlined in my navigation bar when a user is on that particular page. I have used CSS codes I found on here like:

.main-navigation ul.nav-menu > li > a:hover {
text-decoration: underline;
}

But it does not seem to do the trick. I added it to the bottom to my style sheet and also the custom CSS box that comes with the Theme under Theme options.

website: http://www.dgcuts.com