Firstly, good on you. If its worth doing, its worth doing right, even if it means tackling CSS layouts for the first time, which is a scary time for all of us
I'll have to go over this again sometime if problems persist because I'm tired, its late, and I skimread it. A word of advice though; KISS. Keep It Simple Stupid. Part of the beauty of CSS is its simplicity. I mean hell, whats the complex computer speak you need to make a paragraph red in CSS? color: red. Now, layouts are seldom that simple, but if you are trying to place a box there, do not turn it into pass the parcel, then hope one of them is defined correctly. Part of the concepts behind CSS is a seperation between presentation and markup, so avoid any presentational markup; no <b>'s, no structual <br />'s, and definately no <center>'s, but also no nesting elements for the sake of a specific technique. Sometimes its good to add hooks, extra classes and element structuring, for later presentational flexibility, but divitis seldom helps.
Sleepy rant aside, floats can be very moody, particuarly in IE, and if they don't have the right room, they just jump out the way. Besides IE having some float issues anyway, different browsers have different default styles for elements, critically, these include margins and padding, so unless you define these for everything (or just wipe all at the start with the * selector), your sizes are going to be different crossbrowser.
Now, floats not being ideal for positioning like this, we fall back to CSS's simplicity. Want to position an element? Try position
"position: absolute;" will absolutely position an element where you define it to be, using top, left, and/or bottom, right properties, absolute to the page. "position: relative" will move it relative to where it would be (static being where it normally is), and fixed would place it fixed in the viewport, so won't move when you scroll. Lost a fantastic article that would clear that up better, but I can still offer a link to a site devoted to simple layout techniques.
Read this (glish.com/css/)
