The left and right columns have widths of 5em.
In an attempt to use all the available space,
the middle column has been set to 'auto', and text has been added. The right column has been floated right. The middle column is no longer floated.
Left
mmmmm
Middle
At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd
gubergren, no sea takimata sanctus est.