OK, since I got no other feedback on topic...

I looked into it, and there are not many things we seem to be able to do about it ...

... except to change the default CSS for textareas.

textarea {width: 100%;tab-size: 4;}
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in line 173 of common.css

There is no way for a simple pmdev like me to provide a better patch.

/* This CSS controls presentation details common to all six original t
+hemes. */

/* This CSS has been moved to a regular file on the server(s), for
   performance reasons. If it needs to be altered, chat with a god.
   If it doesn't, chat with a god anyway. Gods are people, too. */
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hence I'll message a link to this post to the gods and pray... :)