Created by: dgrammatiko
Changes
The selector :not(:first-child) is changed to tbody:first-of-type so that the border-top has consistent results if there is or not a caption element
The problem is reproducible if the table has a caption element but the caption is visually hidden
For reference: https://github.com/joomla/joomla-cms/pull/35766#issuecomment-943248219