CSS: How do I arrange 3 elements into columns with the middle element filling in between them?

I have 3 elements I want to arrange into columns.开发者_StackOverflow中文版 I want the left and right elements to stay fixed widths and align to their respective edges of the page, but the middle element I need to fill in the space between them.

How do I do this?

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Age old question, solved by the geniuses at ALA: http://www.alistapart.com/articles/holygrail/