Hello Jean-Luc

Thank you for your purchase.

What you're trying to achieve can be done with some simple CSS. In wpDataTables settings/Custom JS and CSS/Custom CSS field, you should add something like this:

table.wpDataTable .group {
color: green !important;
font-weight: bold !important;
border-color: red !important;
border-top: 2px solid !important;
border-top-color: red !Important;
background-color: wheat !important;
}

Here's the screenshot from the menu itself:

And the result in the table would be:

I hope this helps.

Great news, Jean-Luc

You're welcome. Glad I could help.

If you have any further questions or issues, please feel free to open a new ticket, and we'll gladly help.