Theme for non-editable text

[Alan Smith]

When I set the EDITABLE flag to false on a Blockly.FieldTextInput it gets rendered (with the classic renderer) as a black box with white text.

I am having trouble finding out where to change this (say to dark grey text on a light grey box for example)

I can tell that it is being set to the CSS .blocklyNonEditableField 

Do I just need to change the CSS or is there theme support for this?

Thanks in advance,

Alan