How to auto adjust Customer comments to text height

[rafitin]

Hi all.
OTRS version 6.0, Community, on premise
I want to auto adjust the height of the MessageBody in Customer portal, when the customer review the comments.
As you can see in the image, i can modify the height to a fix value but i can't setup to auto adjust to the text height inside body message.

Untitled.png

Thanks in advance for your help!