please remove the .form-input width setting. I found a better way to solve it. Go to extra properties and add:

.body_col textarea.form-input {
width: 99%;
}

This fix it for me and you can resize the browser window all the time and it work as it should.

my board: http://www.dragonclan-forum.de
my hobby: http://www.biker-reise.de
Ich kann bei Fragen zu UBBthreads in Deutsch weiterhelfen oder es zumindest versuchen