Using the following CSS in the rowStyles attribute of a table plus macro:
... used to correctly set the header background to a dark blue.
After the recent upgrade of confluence, the blue color flashes momentarily and is replaced by a light grey. It appears to be coming from this style:
Note, I've tried running in safe mode with only the Advanced Table add-on enabled with the same result.
Also, the result is the same whether the space uses the documentation theme or the global theme.
Confluence Server 5.10.8