Wordpress Nav-Wrapper Breakpoint Tablet

After searching a couple of hours,

I am coming to you with a simple but yet unresolved issue :

I have a wordpress website, with a theme I bought. My toggle menu (responsive menu) is not showing properly on tablets and other 1024 devices (some items are overlapping). Since I don't want to remove any item or play with its size, structure etc... I would like to change the breakpoint between displayed top menu (for all resolution above 1024) and toggled menu (1024 and less).

I don't find any @media or min-width in my style.css. The objects used in my themes are nav-wrapper.

Any idea how to do that quickly and easily through custom css?

Thnks again,