How to Make the Content 100% height and equal height columns in this layout?

Question

I have this layout where the my_menu is fixed at the top, followed by header, followed by content with 960px and centered, in which 3 columns have been floated left and fina

Answer 1

AFAIK this isn't possible with pure CSS without using grid layout or flexbox which are both not very much supported in the browsers. (Flexbox is at least already w3c working draft...)

You can work around this by applying min-height, which has several drawback, or set the height via js. I don't know any reasonable crossbrowser css-solution atm.