Thanks for your answer.
I already try this option but i have a problem because, i add my class in the submenu and not in level 1.
It's perfect, i just add this line :
and it'is ok.
You're welcome! I would use a more logical class name. How ever, please mark my above answer with ✔ to close the question.
I also tried your suggestions. I added some CSS class to the parent (level 1) menu but it doesn't show up in the dropdown. The dropdown classes are just the same after saving and refreshing the page, like the following:
uk-navbar-dropdown uk-navbar-dropdown-dropbar uk-open uk-navbar-dropdown-boundary uk-navbar-dropdown-bottom-center
Am I missing something? Did I do it in a wrong way? I actually put the CSS class to this field called "Link CSS Style" in the menu manager of Joomla.