Cell width

I am trying to reformat my XSLT presentation page (several tables)
so that some cells are shorter, some are longer
and in some rows the text spans across a few cells.

As of now, it all render them as all of the same width.
Is there a tag in XSL for that, something like a "colspan" in HTML ?

Can the number be less than 1?  (my first column should be very short,
just a few characters)

Thank you,
Oleg.