How do I add padding to logo

Hi
I have set the header height to work well with the logo. However when I scroll the page & the header shrinks there is no padding top & bottom of logo.

Do I need to create new logos with padding, the issue is that the padding effect shrinks in proportion to the logo shrinking.

Or is there a CSS code I can add to give padding to the logo when it shrinks when scrolling.

Thanks Dave