Here is the link of the mobile Epik demo: http://my.studiopress.com/themes/epik/#demo-phone You can see the logo: “Epik”, right below using the same background color (dark grey) you can see the nav links (custom menu widget).
With my website, you will see the logo on top just like in the demo, and right below you see the nav links (custom menu widget) but with a grey background color instead. This means that the header responds and extends the height for tablet/phone but with my site it stops at 77px because of the line of code I added.
If i remove that line of code (height: 77px), the site will respond to tablet/phones but then in the desktop version the height is doubled.
Hope you can see what I am trying to explain. Thanks again!