Foldable markers in customize buffers are almost invisible

[andreyorst]

What happened?

Here's how triangle buttons look with doom-one-light:

And with doom-one:

Also happens in doom-dracula, doom-gruvbox, doom-henna, doom-spacegrey, and almost all other dark themes.

I suspect that this is due to most of those having shadow face way to close to the background:

But I'm not sure, as I can't find what face this button uses.

What did you expect to happen?

Steps to reproduce

1. enable doom-one
2. open customize

System Information

• Emacs version: 28.0.50
• Emacs distro: None
• Operating system: Fedora 34
• Installed commit of doom-themes:20f9eb93a28817eb39b39899022c2971e015e49d
• Which theme are you using: doom-spacegrey