Personallized CSS is a wonderful thing, but If I remember correctly, some browsers won't recognize CSS width/height attributes on textareas if said textareas are defined with "rows" and "cols" attributes (which the PM textareas are).

I've never really minded the size of the textarea, but now that it's been pointed out, and given the push to make PM more CSS based, it seems like switching the textarea sizing to use CSS for sizing would be a good idea. and the example you listed seems like a good site default.