Hyphens, En Dashes, Em Dashes

Q. The clarification on compound color hyphenation in the 16th edition is greatly appreciated, but my coeditors and I still disagree on a problem common in fiction: do general modifiers such as “dark,” “light,” or “bright” count as compounds when used with a color (“dark-blue tie,” akin to “midnight-blue tie”) or as a set of distinct adjectives following Chicago’s preference for minimal hyphenation (“dark blue tie,” akin to “old blue tie”)?

A. It depends on their meaning. If the blue is dark (or midnight), it is a color compound and can take a hyphen. But “old” refers to the tie rather than some outdated shade of blue, so “old blue” is not a compound, and a hyphen (“old-blue”) makes no sense. Consider too that when the meanings of two versions (“dark blue tie” and “dark-blue tie”) are so close as to be indistinguishable, it might not be worth your time to worry about it.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]