Header height in Wordpress

I give up! For the past 3hrs, I was trying to figure out how to change the header height, in one of the Wordpress themes.

Here is the demo: http://ift.tt/1HqVUrk

So far I have only found this rule in style.css on line 287:

.bg-image {
  height: 210px;
  width: 100%;
}

BUT, there is something else that is overrides this, because if I delete height completely, the header still remains the same height...

I'm completely lost, please help!

Cheers