Borders not shown in Firefox with border-collapse on table, position: relative on tbody, or background-color on cell

Answer 1

Another possible solution is to correct colspan errors in your table markup.

Apparently can colspan errors cause the same effects with hidden borders when using border-collapse: collapse;

I was directed to the right solution through http://www.codingforums.com/html-and-css/46049-border-collapse-hiding-some-outside-borders.html.

In my table I had written <th colspan="9"> when there was only 8 columns.

That caused error (hidden right border) in

• Chrome 51.0.2704.103 m (64-bit)
• Vivaldi 1.2.490.43 () (32-bit)

but rendered with right borders in

• Firefox 44.0.2
• IE 11 (11.420.10586.0)
• Edge 25.10586.0.0