Logo image not responsive and not showing on mobile devices – Theme Expression

Hello there,

I’ve been trying to solve this problem for a long time but I can’t find the answer!

I have a custom logo I’d like to add it to my header, I’ve tried with different image sizes and I’ve been using the one that adjusts best to the header. What I can’t find is the way to make this image responsive, when using a mobile device the logo doesn’t display in the home page and when browsing other pages it appears below the menu, out of place.

This is the website:

http://www.duo-klier.com

Using WordPress 3.5, Theme Expression (by brainbuzz media)

Many thanks in advance,

Pablo