runfix: change dark mode slow indicator styles

[PatrykBuniX]

Description

Fixes the styles of slow connection indicator in the dark mode using css variables (as requested by the design team).

Screenshots/Screencast (for UI changes)

Before:

Now:

Checklist

• [x] PR has been self reviewed by the author;
• [x] Hard-to-understand areas of the code have been commented;
• [x] If it is a core feature, unit tests have been added;

Important details for the reviewers

(Delete this section if unnecessary)

• use (x) data
• can be reviewed commit-by-commit
• be sure to look at ...

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud