Change size on menu but not sub menu athens 2.0

Store Design
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1

Hello, is there anyone who can help me understand how to adjust the size of the main menu without affecting the sub-menus?
https://www.remlagret.se/

emilbrandon_1-1698145448885.png
emilbrandon_1-1698145448885.png1164×602 72.6 KB

2

Yes, with some help and guidance i can manage.

3

yes, if you have a code for this please assist me.