I like to use upper case letters in my css color values. To me, it just looks better, and makes it easier to tell if there's a missing or extra digit. Whatever... To each his own, right? Especially since CSS doesn't care.
Well, after tearing my hair out for three hours last night, I finally figured out what was causing the totally spurious behavior of my theme's color module integration...
The Color Module is intolerant of upper case letters. It reads #45C690 as #000000, and proceeds from there. So you basically get kind of a dark mode thing going for all your color configurations, and it stays that way until you save back to your default.
This is just a heads-up for anyone who might be experiencing this issue.
That seems odd. I just spun up a demo site and used the color module with the Basis settings. Added an upper case hex colour, saved and it worked.
Perhaps you could give a few more steps to reproduce the error?
The issue shows up when you include upper case hex colors in your css file, and the Backdrop Color Module tries to process it (doing color substitutions). It croaks on upper case text.
The color module is in core. We have a META issue for existing color module issues and I don't see an open issue for this problem. Feel free to create an issue in the core issue queue.
This comment is just to clarify an error I made in reporting this issue.
I was mistaken. Whereas I reported a problem that occurs when upper case hex values are used in the CSS, that was not the problem.
The problem only occurs when upper case is used in the 'color.inc' file by the theme developer.
Sorry for my knee-jerk reporting on this.