I ran into a similar problem. I solved it by adding this into the beginning of stylesheet.css:
#header { padding: 0 !important; }
.container-inner { padding: 0 !important; }
.container { padding: 0 !important; }
.group pad { padding: 0 !important; }
#header .pad { padding: 0 !important; }
.site-title { padding: 0px 0px 60px 0px !important; }
It gets rid of all the padding and spaces on the sides. This works with my specific image, which is 1380×200. Customize it to your own liking.
P.S. Ma olen ka eestlane.
