Drop shadow navigation bar

Shopify Expert
16 0 3

hi there!

I'm looking to add a drop shadow to the bottom of the navigation bar, I've tried out a couple of codes from other threads but nothing worked so far. Could anyone point me in the right direction?

it's for https://infratechdigital.myshopify.com/

and would like the shadow to have this look (I know it will look slightly different on our homepage tho, as it has a dark header)

Screenshot 2020-11-30 at 10.49.02.png

Thanks so much!