using CSS extend div heights of all divs in a row as content adds in one single row

I've 3 divs as columns in a single row using CSS float left attribute and I want to increase the heights of all the columns as content adds up in any column so that the height of all the 3 开发者_如何学编程columns remains relative to the initial height. How should I do that?? (I'm using 960 CSS grid)

give the container a defined height (i think the classname is container_12 or container_16) and set the grid class you're using to height:100%;display:block;.