Ι had the same problem.
go to the menu make a link give it a name put it in the menu and save
then delete the url from the link
in this way you made a fake page to give a name of the category you want
then make pages and put them down from the fake title you made
finally to make the effect put a new plugin with the name max mega menu
enable it in the left of the menu and play with the colors in the settings of this plugin!
good luck!
customize widjets video widjet
