Hi Mr Papa, I’m fairly new to the SP structure but I finally found the css 
I’ve just gone through the sp-pm.css and no mods have been made, all files were modified on 24-4-15 so it’s recently updated.
#spMainContainer #spPmCount .spPmCountUnread {
color: #ff0000;
They are using original overlays (no child) and also using renamed duplicates of originals while experimenting with the colours and gradients.
With the various overlays tested the colour of PmCountUnread is anything but red (excluding light-red overlay), all overlays are showing their default colour for inbox button text.
I’d download the tables and uninstall the plugin to re-install but the host is tight with SQL usage and has already stopped me using the 250 and 500 rows view after a week of cleaning up, I really don’t need any more restrictions placed on access.
I’ve hit a brick wall with this one 