Dreamscapes

So it seemed from some of the discussion on other layout comms that users wanted something like LJ's Expressive/Mixit styles, which for those unfamiliar with them, are fixed width and have pretty header images.

Now, I know we don't do fixed-width-by-default here, but I decided I'd try my hand at something that could be set between fluid and fixed width very easily, and supported header images above the header text, as well as behind it. The base once again is branchandroot's Paletteable because apparently it's my go-to for a clean starter code *g*

Source is here, and you can see it live here, though the back-end stuff is where the magic (and thus the feedback-needed is).

Stuff I plan to do for sure:
-make the sidebar background extend the length of the page (and in fact thought I had, up until, uh, right now)
-Style the month headers on archive-page-by-year to look like the subject headers on entries.

Stuff I am waffling about:
-right now the image input for the header is the same as the background header-image, with a toggle between the two. I'm not sure if it should stay like that, or if there should be an option to have header background /and/ a banner-header.
-Not sure what other CSS tweaks I should make because... I am not always an ideas person *g*