Fix issue #3218

[Nazeeh21]

Earlier, on route localhost/tree/docs the word "running" appearing next to the file name of the new notebook was failing the color contrast.

Before fixing

After fixing

**On route localhost/tree#running (a new notebook is running) kernel-name wasn't too dark.

Before fixing

After fixing

For new notebook, on route http://localhost/notebooks/docs/Untitled.ipynb the contrast for kernel_indicator was failing.

Before fixing

After fixing

Fixes #3218

[kevin-bates]

HI @Nazeeh21 - the screenshots are greatly appreciated, these changes look good to me - thank you!

[Nazeeh21]

@kevin-bates thanks for approving the changes 😃 and for all your support. Looking forward to my PR getting merged.

[kevin-bates]

Hi @Nazeeh21 - in speaking with some colleagues about his PR - which looks good, they suggested that comments indicating that the particular lines were updated for the purpose of accessibility be added, perhaps something like // accessibility improvement? Would you mind updating the PR with those?

(Sorry for the delay in getting back, I just realized that I had never submitted a comment similar to this one a couple of days ago.)

[Nazeeh21]

Sure, I will add // accessibility improvement before every line changed in this PR. Also not an issue for this. 😊

[kevin-bates]

Thank you for the update @Nazeeh21!