Update colors for compatibility with the dark theme

[codecov-commenter]

Codecov Report

Patch and project coverage have no change.

Comparison is base (1e781c6) 93.29% compared to head (00eb7a5) 93.29%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #701 +/- ## ======================================= Coverage 93.29% 93.29% ======================================= Files 47 47 Lines 3905 3905 Branches 579 579 ======================================= Hits 3643 3643 Misses 152 152 Partials 110 110 ```

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[zerolab]

Hey @spikenn,

Would be good to have some screenshots -- before & after with the dark theme, and how the changes look with Wagtail 4.1

[tspnn]

Hi @zerolab

Wagtail 4.1.6 - some CSS variables are missing Wagtail 5 (dark, before) Wagtail 5 (dark, after) Wagtail 5 (light, after)

[zerolab]

Thank you for that, the UI does look much better in dark mode with these changes. It would be good to add the missing CSS variables for 4.1 as that is our long term support version and it would be unfair to make the experience worse

[tspnn]

@zerolab I added fallback values, now it looks better.

Wagtail 4.1.6

[zerolab]

That is most excellent, thank you @spikenn

Will test locally this evening and if all is good, will merge and package it all up for a release

[zerolab]

By way of update -- this needs more work on consistency. I am chipping away slowly at it. May be a Friday release

[zerolab]

Merged manually in b60a60056452f6e06dd588bb16411619f3cd0e0d + parents. Thank you @spikenn

[zerolab]

v1.5.1 is now published