Been absent a while, I know. But I'm back now. :D
I know I've done this before with other themes (and I can't find the code in them, and my wiki where I was keeping all these gems was hacked and is now down), but I just can't for the life of me work it out right now.
I'm using Moodle 2.4, but it applies with any of my themes in Moodle 2 that are based just on Base.
At the top of my page (above body) I have a gap that, no matter how much I Firebug it, I can't identify its origin. I have margin: 0 and padding: 0 in all conceivable locations.
Then at the bottom of the page (below html) I have another gap. The body part of the page stops just above the footer, but the html part encompases the footer. However, below the footer / html part a gap that I can't get rid of. Again, I have margin: 0 and padding: 0 in all places anywhere near there.
I know once I am told I'll kick myself.