As it is, when the whole object is squeezed into a center column there's too much wasted space, so I want to make that column more narrow.

I've tried adding

width ="70%">

width="5%">

but Forum column will only grow to about 50%, and LastPost column won't get any smaller than it is.

suggestions?

Try to add this to your theme....

.yafnet .lastPostCol {
      word-wrap: break-word;
      width: 5%;
}

.yafnet .lastPostCol {
      word-wrap: break-word;
      width: 5%;
}

That didn't change the column width of the forum list, but it DID change the last column width of the topic view....weird

If so, is this possible?

.yafnet .headerLastPost,
.yafnet .lastPostCol {
      word-wrap: break-word;
      width: 5%;
}

It worked on my site with my theme

.yafnet .headerLastPost,
.yafnet .lastPostCol {
      word-wrap: break-word;
      width: 5%;
}

Thanks for looking into this; must be a problem on my end; your changes effect my default.aspx?g=topics display last column perfectly, but have no effect on default.aspx?g=forum display

It depends what you actually add to your theme, with the code i posted above it should work on both pages.