This style for Google Calendar colors the Year View Lab gadget canvas and shifts it to the right to more center it in the window (though you'll probably have to adjust it manually if you want it really centered--I sized the padding here for a window of about 1150px width).

Updates...
19Jul2010: fix to change the highlighting Google added for 'Today' recently--today even (25Jul2010: and now it's gone... granted, it was kind of pointless, but it didn't get in the way either, so, no particular reason to remove it [meh]) (27Jul2010: and it's back! [will probably go missing again next week])
18Jul2010: uhhh, never mind... I found the controlling domain for the iframe (after actually looking at it right [duh])--back to blue
18Jul2010: commented out the first statement because it can set the background color for more than just the Calendar page--Google help pages for instance (oopsy... though it doesn't look all that bad really :D ...yep, fun with iframes!), so instead of that blue you see in the 'After' screenshot... it's gonna be the default white.