I tried applying overflow:hidden, text-overflow:ellipsis, and display: inline-block to the span and adding a width value for the table cell, all through a stylesheet. (Display:block on the span doubled the height of the row, which I didn't want, so inline-block was my choice.) The title text appeared truncated, just as I wanted. But the table wouldn't get any narrower.
After messing around changing values and styles through IEDT I concluded that, when figuring out how narrow the table could get, the text was still counted as being its full length. The span was relatively short, only the text that appeared in the span appeared, but for table-cell width purposes, the text was still all there.