This code creates a nice vertical scrollbar for me in Firefox and Chrome:
#answerform {
position: absolute;
border: 5px solid gray;
padding: 5px;
background: white;
width: 300px;
height: 400px;
overflow-y: scroll;
}
_x000D_
<div id='answerform'>
badger<br><br>badger<br><br>badger<br><br>badger<br><br>badger<br><br> mushroom
<br><br>mushroom<br><br> a badger<br><br>badger<br><br>badger<br><br>badger<br><br>badger<br><br>
</div>
_x000D_
Here is a JS fiddle demo proving the above works.