README in Dark Mode has Visibility Issue

[mindlessroman]

Describe your bug
Minor visualization bug - in GitHub Dark Mode, the header at the top of the README is very hard to read. It's worth considering giving the images a distinct background instead of transparency so that it's visible in both light and dark mode.

Distribution Information:
n/a

Node Version:
n/a

To Reproduce
Steps to reproduce the behavior:

1. View this repo's README with GitHub's dark mode selected.

Expected behavior
Improved visibility.

Screenshots
See above.

Additional context
n/a