Overwrite default CSS

Hi!
Is there a way to overwrite the default css classes?

I’d like to design a dropdown with full width list items. However the style “list-horizontal-layout” overrides the desired 0px margin on my custom style. How can it be fixed?

Thanks.

after you export the website. you can use the browsers developer mode to find and test the css.
and hand code them in the style.css file

at least thats how i do it