Css Variable Length Columns Extending Too Far

Not a front-end UI but have a (probably) very easy problem to fix. Here is a jsfiddle of it: http://jsfiddle.net/trestles/U7mYT/ I have two floated elements shown in this screen s

Solution 1:

I don't know why you should use positioning for the divindex-right-content. Also, the width is more than it should be... I think I see 640px for the width, which I think is unnecessary, provided that the widths of the columns inside this div is defined.

Solution 2:

see the updated jsfiddle adding float to both inner columns in container.