Sticky table header with colspan/rowspan

[Rasputin93]

Describe the Bug

My wiki uses the TabberNeue extension.
Sticky table headers don't work as expected when using colspan or rowspan properties.

Steps to reproduce the behavior:

1. Go to https://rammwiki.net/wiki/RammWiki:Test5
2. Scroll past the table header.
3. The last part of the sticky header shifts to the right, second header row isn't sticky.

System

• MediaWiki version 1.43.3
• PHP | 8.4.10 (cgi-fcgi)
• MariaDB | 10.11.13-MariaDB-log