size of header in atahualpa 3.4.9 theme

My website is https://www.thewealthwisher.com. I want to have my header colour (blue) way to the right of the header and I do not want to increase my header width for this. I want to use the background colour of the header area to merge the header (like https://thewealthwisher.blogspot.com/). At the same time I do not want to shrink width of my front page. How can I do this ?