Color is not claimed as a feature of the mark.
The mark consists of a design consisting of the letters "C" and "M" as solid characters occupying the same space with overlapping areas of the two letters being the same color as the background. Combined with the literal element, "Salter's The Culture of Money" in standard characters.
C M SALTER'S THE CULTURE OF MONEY; M C SALTER'S THE CULTURE OF MONEY; MC SALTER'S THE CULTURE OF MONEY