This is a fluid* column meaning that it expands to exactly 20% of the available width in the body.
* to test this fluid layout, resize your browser window and you'll notice that the column sizes will shrink/grow accordingly.
This middle column is fluid* as well accommodating 70% of body's width ideally to display more info in the middle - a traditional blocked layout of many portal-like websites.
One of the main arguments to use tableless design is to separate markup from style which, if used smartly, should improve the overall experience, including speed.
This is a fluid* column meaning that it expands to exactly 20% of the available width in the body.