So what do you want 100% width — the header or the content (or both)?
If you are referring to the header only, there is a way to do it. This was covered in a post about four or five weeks ago. I don’t have time to find it right now, but if you’re interested, take a look around and I’m sure you’ll find it. (It looks very weird, but it’s possible.)
If you are referring to content, you really don’t want to do that, because of monitor size. Read this:
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