Using CSS Data from Within My Code

[Ron Tarrant via Digitalmars-d-learn]

I found this presented as a solution in a 2016 post:

On Wednesday, 15 June 2016 at 22:05:37 UTC, captaindet wrote:
enum myCSS = q{
    GtkNotebook {
        background-color: #e9e9e9;
    }
    GtkNotebook tab {
        background-color: #d6d6d6;
    }
};

But when I try to use it, I get the following errors:

Warning: C preprocessor directive #e9e9e9 is not supported
Warning: C preprocessor directive #d6d6d6 is not supported

I thought it was odd having 'q' in front of the opening curly 
brace... is this a typo? Shorthand for "string quote"? Something 
like that?

Or do I need to escape these somehow?