Fun little scientific fact when comparing to the other three staff colors of current (Roleplay Judge, Administrator, Factory Judge).
Cyan is the optimal contrasting color for the Codex. Which is neither blue nor green, but both. You were close.
Personally, the fact that cyan factually just works notwithstanding, I also believe they are too similar in color with the RPJ group. Not everyone has the brightness, contrast or gamma settings on their systems or monitors to build a truly discernible distinction. While they might appear different to some with a keen eye, there are simply places where there just isn't a visual difference.