HTML table colgroup element not working?

Set your table-layout to auto instead of fixed...

table {table-layout: auto;}

My personal site supports multiple themes and I see these kinds of differences all the time.

You could use css selectors to get similar results without adding extra classes.

As an example if you want to give specific style to a second column you can use:

table>tbody>td:nth-child(2){font-weight: bolder;}

That's correct. While colgroup itself is supported by all browsers, this isn't true for the attributes of the inner col element. Of possible attributes, only width is supported on all browsers. But unlike CSS, <col width=""> only supports pixel and percentage widths.

Don't use it. Instead, create CSS classes and assign them to each td. Yes, it sucks.

EDIT Updated link above to page with better information