These divs create columns that will float side by side. This is the div with an id of column1 and a width of 150 pixels. I am typing in nonsense text to give the column some substance.

This div has an id of column2, with a little more text so it is a different height than the first or third column.

Aslett uses the CSS :after pseudo class to add content & force the container to enclose the floats. It requires a class to be added to the markup.