Full page width header in catch box theme

I am looking to have my header and nav bar run the full page and leave the main content stay at the normal 1000px.I have an image as my header currently, and I plan to change it if I can figure out how to get the header to the full view of the browser screen. I am trying to get a look similar to the header on this wordpress.org header above, as far a width goes.

I have found in the style sheet where to increase everything but I can’t seem to find where to edit the header width independently. If anyone knows please share.

My site:

Thanks