The recent CSS cleanup for the review request page left out a CSS rule

for setting position: relative on the the review request field

sections, which messed up calculations when trying to determine the

ideal height for the last review request text field in the main area.

This meant that they ended up taking up the natural field height instead

of expanding to fill the available height.
This is a simple change that just adds the missing CSS rule.

Tested with a blank review request, and saw that the bottom-most text field

took up the available space.
Tested also with other review requests containing a lot more content. They

appeared correctly as before.