How do i make a fluid float:left layout?

For example, i'd like to have a grid of boxes all floating left. I have the design here: atbskate.com/trusktr.

The boxes on my site are all float:left. However, when i expand a box by adding content into it (ajax) it shifts the other boxes and leaves an ugly empty space. I'd like for the boxes to fill up this empty space.

The idea would be similar to http://www.robclarke.com/. when you click on a box, it expans, and all the other boxes are shif开发者_如何学Cted and there is no empty space. How can I avoid this empty space?

The code on robclarke.com is very complex so i ahven't had time to disect it...

Any ideas?

Have a look at the jQuery masonry plugin which provides for a lot of flexibility in handling content in boxes.