Thank you, I've come across one (1) magazine with custom CSS and it didn't take the font colors in kbin's dark themes into account.
(The mod was super cool about it and reverted the change until a better solution could be found, but I knew then I would need this option in the future)
Thanks very much for this. I really appreciate that the option to customize exists for people who want it; equally, I appreciate that the option to NOT have customizations exists for me :)
Disabling custom CSS everywhere was always a built-in option, as I recall. RES added the ability to disable custom CSS for individual subreddits, which reddit later added as a reddit gold feature.