Network Graph doesn't work with Dark Mode

Summary

The network graph shows black text on a dark background, making it practically unusable.

Steps to reproduce

Go to https://gitlab.com/-/profile/preferences and select "Dark Mode (alpha)" Try to view a network graph for a project.

Example Project

The network graph for gitlab itself doesn't load, so here's a random publically visible project (that I have no association with) https://gitlab.com/MatrixAI/open-source/js-polykey/-/network/master

What is the current bug behavior?

Dark text on dark background.

What is the expected correct behavior?

Light text on dark background.

Relevant logs and/or screenshots

Output of checks

This bug happens on GitLab.com

Results of GitLab environment info

N/A

Results of GitLab application Check

N/A

Possible fixes

N/A

Extra thoughts (aka out of scope for this issue)

By the looks, the network graph could do with some TLC, the branch tags are truncated and hard to read due to transparency. I'd like to be able to link the network graph to some of my non-developer colleagues so they may review version numbers (deployment history) and the status of any feature branches.