textarea background problem

I want to customize the text area form, and I use a red border image as a div background, and put the textarea inside of the div, but on the top right hand side, and bottom right hand side, thre scroll bar blocks the corner， is there anyway to fix this?
Here is my code

 
<div class="<?php if($errors_switch[0]) echo 'redcomments'; else echo 'comments';?>"><textarea name="comments" id="feedbackcomments"><?php if(isset($_POST['comments'])) echo $_POST['comments'];#SHOW ENTRY IF ANY ?>
</textarea>
</div>