Problem with tgroup width using XSTL

Hello,
I'm trying to use a table with several tgroup inside it, and resulting HTML is 
somewhat wrong.

The documentation for 'tgroup'

    http://www.docbook.org/tdg/en/html/tgroup.html

refers to 

    http://www.oasis-open.org/specs/a502.htm

for processing expectation, and the latter document says:

    All <tgroup>s of a <table> shall have the same width, so the <table> frame
    can surround them uniformly. 

Yet, when I try the attached snippet with the latest XSTL stylesheet from 
sourceforge, I get distinct HTML tables for each tgroup. The result, which 
can be seen at the bottom of

    http://zigzag.cs.msu.su:7813/program_options/html/bad.html

is not as pleasant as I'd expect. Am I doing something wrong or XSTL 
stylesheet is wrong?

- Volodya