AST Colour Issue

Hi, I have set up AST (Advanced Shipment Tracking) and in the customise section I have customised the email however the details below are coloured in pale grey and you cannot see them on the white background. These are the only words affected and I can change the colour pallet for all other text but for some reason I cannot find which Text colour box changes these. Can anyone advise please?

These are the words affected

Order Number
Shipping Address Header
Billing Address Header

(you can see the shipping & billing address as they are black but the header to them is grey)

thanks in advance