Poor text contrast on some diagram labels in dark mode

[kenjenkins]

Page: https://www.pomerium.com/docs/capabilities/original-request-context#example

What's incorrect or missing

In dark mode, some diagram labels all but disappear:

What's the resolution?

Let's see if there's a way to:

• put a background behind these labels, or
• make the label text color dark-mode aware

Docusaurus can be configured to use a different Mermaid theme in dark mode (see https://docusaurus.io/docs/next/markdown-features/diagrams#theming), but the other options I saw didn't seem to help with this issue.

[kenjenkins]

To investigate: is there a specific CSS class for these diagram labels that we can target with a dark mode rule?