History of CSS Layouts, from Geocities on
fantasai.inkedblade.net
fantasai.inkedblade.net
Explanation from the post:
The width you specify isn't an absolute, it's a goal. If 2½ columns will fit, you'll get two columns 45em wide each. If only half a column will fit, you'll get one column 15em wide. So the width might not always be what was specified, but for the reader, the design always fits the screen perfectly. And since the column heights are auto-balanced, the layout always fits the content.