I'm not sure there's a way, as you have it. If you put a wrapper around the red box, and put the red and blue boxes inside it, then you could float orange and yellow to the right of them.
Assuming you want the blue box to be directly under the white and red boxes like a column your problem is that your container height is set too low for the height of the three boxes. I played with it and set the container box to 73px and it fit the blue box right under the white one of the same width. There is a second alternative than setting the height, this involves making a clear div just before the closing of the container tag and removing the height setting altogether on the container.
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