Twenty Eleven – Full Page Width Header possible?

Hi,

I’m working on my new blog over at https://www.postdemise.com

The theme I am using is Twenty Eleven, having ALREADY SETUP A CHILD THEME.

My idea is to make a solid colour gradient fill the whole width of the screen at a 150px height going left and right (yeah, the whole width) from the head image.

How can I achieve this, what do I need to add to my code?

Make sense?

[ ] = Monitor Edges
— = Proposed Solid Colour Block
::: = Header Image

Diagram:

[—–::::—–]

See what I mean? I hope so, although I am pretty tired right now so I wouldn’t be surprised if it doesn’t, sorry.

Also, whilst I’m here… I’ve increased the page width so that the content is spread over a wider space, but I wish to decrease the space between the content and the sides of the wrapper. So, the space between a blog post and the whiteness between it and the wrappers border.

I assume this is just a simple padding tweak, but I just can’t figure which value to change.

Thanks, I really appreciate any help as I’m not really an expert in the web design field.

Goodnight!