Locking a Textbox input stretching to one Axis

Hey everyone, quick question.  I am attempting to lock a Textbox input to a single Axis (Vertical).  This is no problem seemingly in the HTML; I just add  resize: vertical; to the input style and it works flawlessly.  Yet every time I try to do this in Roll20, it lets me expand outwards in multiple directions, which breaks the sheet formatting. I have several Roll20 character sheets that have successfully locked a textbox to a vertical input, but I can't figure out how they did it.  Is there some trick to make this work on Roll20?

Did you specify a max width?  That should lock it from going wider.

Apologies, I wrote a reply but it didn't post!  I got it working great and wanted to thank you.  That fixed the problem, seeing the minimum and maximum width; merely restricting the axis didn't work but that sure did.  Thanks again!