Thanks for your reply Paul.
I posted in the Arch forum & at ostalk.org regarding this problem; I was told that I should try the Firefox add-on Stylist, which I have done.
Stylist has improved the colours of some sites I use regularly, so that's nice.
I knew that there was a person on our tiny ostalk.org forum who is also an Arch user & has posted quite a few popular "styles".
He responded to my request, with some code, which after another request, which asked if he could put the data following each of From: Registered: & Posts: on the line under them.
He very quickly did this & it works, allowing the user to modify two ***px numbers to suit their resolution & font variables & taste.
So now I have a solution, where I can easily & quickly modify the width of the column on the left hand side of the forum post's content.
Thanks again for your reply Paul.
I'll post the content here, which I'm sure, for all of you in the know is just so simple as to be worthless, but perhaps someone else like me will stumble upon it & it will save them many hours of research.
The 200px figures below, are set to suit my 24" display & 24 point fonts in Firefox & this is for the Arch Linux forum.
Cheers. 
@namespace url(http://www.w3.org/1999/xhtml);
@-moz-document domain("bbs.archlinux.org") {
.postleft, .postfootleft {
width: 200px !important;
}
.postright, .postfootright {
border-left: 200px solid !important;
border-color: #f9f9f9 !important;
}
}
[Edit:] tjwoosta, gave me the following code today which works - it automatically narrows the the column on the left hand side of the post text area, enlarging the text area. People don't have to change the ***px value. I think this ability should be a part of the default FluxBB setup (at the Arch forum at least):
@namespace url(http://www.w3.org/1999/xhtml);
@-moz-document domain("bbs.archlinux.org") {
.postleft, .postfootleft {
width: 11em !important;
}
.postright, .postfootright {
border-left-width: 11em !important;
}
}
Last edited by handy (2010-02-08 10:46:26)