editing menu/logo for mobile and tablet devices

hey,
I’m using the vantage theme and have been trying to finish my menu. For ages I’ve been trying to re-size my logo, as it was very small before. After lots of googling I’ve used the site origin CSS editor and adjusted the px of my logo (I pretty much know nothing about coding though). I’m now happy with the way it looks on my desk top, but if I view my site on a mobile or tablet device I think the logo is to big, especially on an iPad where there is also to much space around the menu. Is there a way to customise the menu size for each individual device?

thanks

elyse
aworldtolive.com