I tested it. Works fine. Great work!
What'd be even better is if people could have custom fonts set but still use the default colours. Size/font isn't an issue but you really should be able to use two out of the three functions and still be able to keep to the default colour (unless you set it manually otherwise), for the sake of multiple forum styles.
Other than that, there's the matter of having to fix your settings every time you edit your profile.
Once that's all sorted out I'd say you're good to go. Also, the ON/OFF button stays as you set it (it doesn't revert) so that's good.