Improve app contrast in dark mode

[haticekaratay]

Description

This pull request is to address the need for improved color contrast in the application's dark mode.

Before:

After:

Fixes #

Change log entry

• Is a change log needed? If yes, is it added to CHANGES.rst? If you want to avoid merge conflicts,
  list the proposed change log here for review and add to CHANGES.rst before merge. If no, maintainer
  should add a no-changelog-entry-needed label.

Checklist for package maintainer(s)

This checklist is meant to remind the package maintainer(s) who will review this pull request of some common things to look for. This list is not exhaustive.

• Are two approvals required? Branch protection rule does not check for the second approval. If a second approval is not necessary, please apply the trivial label.
• Do the proposed changes actually accomplish desired goals? Also manually run the affected example notebooks, if necessary.
• Do the proposed changes follow the STScI Style Guides?
• Are tests added/updated as required? If so, do they follow the STScI Style Guides?
• Are docs added/updated as required? If so, do they follow the STScI Style Guides?
• Did the CI pass? If not, are the failures related?
• Is a milestone set? Set this to bugfix milestone if this is a bug fix and needs to be released ASAP; otherwise, set this to the next major release milestone. Bugfix milestone also needs an accompanying backport label.
• After merge, any internal documentations need updating (e.g., JIRA, Innerspace)?

[pllim]

Would be nice if you can post a before and after screenshots (in dark mode) for comparison. Thanks!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.68%. Comparing base (9515b7a) to head (58623ca).
Report is 5 commits behind head on main.

❗ Current head 58623ca differs from pull request most recent head 6f33aa7. Consider uploading reports for the commit 6f33aa7 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2721   +/-   ##
=======================================
  Coverage   88.68%   88.68%           
=======================================
  Files         108      108           
  Lines       16214    16214           
=======================================
  Hits        14379    14379           
  Misses       1835     1835           

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[pllim]

Thanks for the screenshots but which is before and which is after?

[kecnry]

which is before and which is after?

Before is right (oranger and darker blue), after left (yellower, lighter blue - with increased contrast)

[pllim]

FWIW, does look better. Thanks!

[kecnry]

There are other places that are hardcoded to use the "active" orange (for example: learn more links, slice indicator, active toolbar buttons, sidebar button, etc). Can those be updated to read from here as well or is that included in a planned follow-up effort?

[kecnry]

does this still need text--secondary or does that not add anything necessary?

[haticekaratay]

Yes, It doesn't add anything I can see. Do you recall why you removed it 🙏 , as I built the styles on top of your last changes to the section header?

[kecnry]

those styles may have been absorbed into strike, so its probably ok to get rid of, I'll double check when reviewing 🤞

[kecnry]

Is there anything we can do about plugin marks (Markers, live-previews in any plugin)?

[kecnry]

and does white icons/text on this new yellow work or do we need to switch those to black in dark mode?

Before:

After: