[Limeone]

Problem

Form errors in dark mode. The theme never coloured validation messages, so
ActiveAdmin's #932419 text and #fae6e4 summary block carried over into dark
mode: the message under a field was dark red on the dark panel, and the summary
was a pale block above the form.

has_many headings. ActiveAdmin renders the container as an li when
f.has_many is inside f.inputs and as a div otherwise. The theme's rule
matched only the li, so the div kept ActiveAdmin's #5e6469, which is dim on
the dark page. The li heading's fixed #8494a8 was pale on the light page.

Fix

• Add $skinErrorTextColor and $skinErrorBgColor with Dark variants, exposed as
  --aa-error and --aa-error-bg. The light defaults are the values ActiveAdmin
  already paints, so light forms keep their look.
• Colour both has_many containers with --aa-text-muted.
• Give these pairs the contrast guard status tags already have in
  test/css_check.rb, reject invalid values for the new variables, and add them
  to the README table.

Visible changes in light mode

Light forms are unchanged, but has_many headings are not: the li heading gets
darker, and the div heading gets slightly lighter.

Measured

test/dummy at 1200px, computed colours, contrast against the fill in brackets:

Element	Mode	Before	After
Inline error on panel #25292f	dark	#932419 (1.74)	#f49b9b (6.97)
Error summary	dark	#932419 on #fae6e4	#f49b9b on #3a2224 (6.98)
has_many heading, div, on #161a1e	dark	#5e6469 (2.92)	#b0b8c2 (8.73)
has_many heading, li, on #161a1e	dark	#8494a8 (5.65)	#b0b8c2 (8.73)
has_many heading, div, on #f7f9fb	light	#5e6469 (5.68)	#6b7177 (4.68)
has_many heading, li, on #f7f9fb	light	#8494a8 (2.93)	#6b7177 (4.68)

The has_many markup on the test page was written by hand from HasManyBuilder.

[Copilot]

🟡 Changes recommended

The contrast check can falsely pass invisible transparent text, and the breadcrumb styling produces unreadable white-on-white text with the documented light title-bar override.

2 open issues

• Preserve breadcrumb contrast on light title bars · New
• Reject or composite translucent colours in readability checks · New

What changed in this PR

This PR improves readability in the ActiveAdmin theme by adding mode-aware validation colours and updating breadcrumbs and nested-form headings.

Changes:

• Add light and dark error colours, CSS custom properties, and input validation.
• Adjust breadcrumb colours and style both has_many container variants.
• Add contrast checks and document the new variables with colour swatches.

File	Description
test/​css_check.rb	Adds invalid-colour cases and message contrast checks.
README.md	Documents validation text and summary colours.
docs/​swatches/​fae6e4.svg	Adds the light error-summary background swatch.
docs/​swatches/​932419.svg	Adds the light validation-text swatch.
docs/​swatches/​3a2224.svg	Adds the dark error-summary background swatch.
app/​assets/​stylesheets/​wigu/​active_admin_theme.scss	Defines error colours and updates validation, breadcrumb, and heading styles.

_{Review effort: Balanced}

[Copilot]

🟢 Approval recommended

No active review issues remain for the validation-message and has_many heading styling changes.

No open issues 🎉

2 resolved since last review

• Reject or composite translucent colours in readability checks
• Preserve breadcrumb contrast on light title bars

_{Review effort: Balanced}