Dark Mode isn't Compabile with Secure MR Widget

Summary

When using dark mode, the UI for the MR Security Widget does not recolor correctly

Steps to reproduce

• enable dark mode in your porfile
• view MR with security report
• see coloring is off

Example Project

What is the current bug behavior?

What is the expected correct behavior?

UI should adjust to the dark mode experience

Relevant logs and/or screenshots

Firefox browser

Output of checks

Results of GitLab environment info

Expand for output related to GitLab environment info

(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:env:info`)

(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)

Results of GitLab application Check

Expand for output related to the GitLab application check

(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)
(we will only investigate if the tests are passing)

Possible fixes