Question!

There is no difference, as both are acceptable. I space mine out :x Also "Cannot" is more commonly used soo....Better request a a text replace...I think?

Also I think "can not" is used in a more empathetic way, which I think is fine consider you can not dye certain parts anyways.

I read that as "You have the option to not dye certain parts" which doesn't sound like a tidbit that belongs on a wiki.

Grammatically "can not" is probably correct, but I think it tends to be read differently or have different meanings like the above. For "unable to do" I always use cannot, personally.