fix(web): repair high contrast tokens dropped as cyclic CSS - #901
fix(web): repair high contrast tokens dropped as cyclic CSS#901zerodayz1 wants to merge 2 commits into
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Seven of the ten declarations in the `html[data-high-contrast="true"]`
block referenced themselves:
--border: color-mix(in srgb, white 34%, var(--border));
Per CSS Custom Properties L1 §3 a custom property whose value references
itself is in a dependency cycle and is invalid at computed-value time, so
the declaration is discarded and the token computes to nothing. This holds
even though an inherited value exists — the inherited value is not
consulted — so the intended mix never resolved.
Measured on a live instance (midnight-cinema, Chrome), all seven
self-referencing tokens computed empty while the non-self-referencing
`--foreground` and `--ambient-glow-opacity` applied correctly.
Two things went wrong as a result, and both made high contrast *worse*
than standard mode:
- `--surface` was invalid, so .surface-panel / .surface-panel-subtle /
.surface-panel-raised computed `background-color: rgba(0,0,0,0)` and
rendered transparent — settings panels, cards and popovers became
flat holes on the page background.
- `border-color` fell back to `currentColor`, and the same block sets
`--foreground: #ffffff`, so borders rendered pure white instead of
`rgb(40, 40, 46)`.
The fix gives the mix an input that is not the property being assigned.
Each theme now defines the literal under `--<token>-base`, the semantic
token is an alias, and high contrast mixes from the base. Verified
against the compiled output in a real document root: all seven tokens
resolve both with high contrast off and on.
Worth recording that the intuitive alternative does not work — moving the
block to a descendant so `var()` inherits is still cyclic and still
computes empty. Only a distinct input token resolves.
`git log -L` traces the block unchanged to c085b12, so this never
worked. It likely went unreported because any profile with a stored
`ui.custom_theme_vars` override never sees it: those are injected
unlayered and win over this block.
Same failure family as Silo-Server#810 — CSS that parses fine, is discarded at
computed-value time, and surfaces only as a subtly wrong UI. Added
highContrastCss.test.ts as a contract test over app.css, in the shape of
navigationTransitionCss.test.ts: it fails the whole stylesheet on any
self-referencing custom property, and checks the mix, the aliases, and
that every theme defines every base token. Confirmed it fails when the
old declaration is reintroduced.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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No actionable comments were generated in the recent review. 🎉 ℹ️ Recent review info⚙️ Run configurationConfiguration used: Organization UI Review profile: CHILL Plan: Team Run ID: 📒 Files selected for processing (3)
Included review availability: Your plan provides up to 2 included reviews per hour; 0 remain after this review. 📝 WalkthroughWalkthroughThe CSS now defines a per-theme contrast direction. High-contrast tokens use that direction with preserved base values. New Vitest tests validate CSS contracts and WCAG contrast across five themes. ChangesHigh-contrast token flow
Estimated code review effort: 3 (Moderate) | ~20 minutes Merge Risk: ⚪ Minimal · up to High-contrast theme tokens now derive from preserved base values and use a theme-appropriate contrast direction, preventing invalid self-references and preserving readable colors across supported themes. No current merge-blocking risk is identified. 🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (4 passed)
Full details: Docstring CoverageExplanation Docstring coverage is 28.57% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 7 functions across 2 files. (1 skipped: 1 unsupported.)
✨ Finishing Touches🧪 Generate unit tests (beta)
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Inline comments:
In `@web/src/app.css`:
- Around line 780-786: Update the cinema-light high-contrast theme overrides for
--muted-foreground and --border to use darkening mixes or explicit accessible
values with sufficient contrast against the background, while preserving the
other theme tokens. Add computed contrast checks covering each theme’s relevant
foreground and border values.
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🪄 Autofix
Fix all unresolved CodeRabbit comments on this PR:
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web/src/app.cssweb/src/highContrastCss.test.ts
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Addresses review on Silo-Server#901. 1. High contrast made the light theme unreadable. Every override mixed toward hard-coded white. That raises contrast on a dark theme and destroys it on a light one. Computed against cinema-light's #f4f4f6 page: --muted-foreground 5.42:1 normal -> 1.36:1 in high contrast --foreground n/a -> 1.10:1 (#ffffff on #f4f4f6) So the accessibility mode drove body text to near-invisible on that theme. The --foreground half was already live before the cyclic-token fix, since it never self-referenced; repairing the cycle would have activated the rest. Each theme now declares --contrast-boost — white on the four dark themes, black on cinema-light — and every override mixes toward that instead. On cinema-light this gives 15.49:1 for muted text and 19.12:1 for body text. The dark themes are unchanged apart from --ring, which moves from oklch(0.95 0 0) to the boost: a negligible shift there, and the difference between a visible and an invisible focus ring on the light theme. :root defaults the boost to white so a theme that omits it degrades to the previous behaviour rather than to an invalid value. 2. Type errors in the test added by the previous commit. `tsc -b` failed on two `string | undefined` index accesses, so `npm run build` was broken on this branch. `vite build` does not typecheck, which is why it passed and I missed this. Fixed, and the new test was written against the same strict settings. Adds highContrastContrast.test.ts: computed WCAG ratios per theme, asserting the boost contrasts with its own page, body text clears AA, and neither muted text nor borders come out worse in high contrast than they were without it. Asserting the declarations merely exist could never have caught this — the tokens were all present and correct-looking. Confirmed the guard fails when cinema-light is reverted to boosting toward white. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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Good catch — reproduced and fixed in fbd726a, and it was worse than the comment Computed against cinema-light's
So it was not only muted text and borders: Rather than a cinema-light-specific override, each theme now declares Added the computed contrast checks you asked for: Also fixed in the same commit: two Validation after the fixes: I have also rewritten the PR description to follow |
1 participant
Problem
Related issue: N/A — narrow bug fix.
High contrast mode has never worked. Seven of the ten declarations in the
html[data-high-contrast="true"]block referenced themselves:Per CSS Custom Properties L1 §3 a
custom property whose value references itself is in a dependency cycle and is
invalid at computed-value time, so the declaration is discarded and the token
computes to nothing. This holds even though an inherited value exists — the
inherited value is not consulted — so the intended mix never resolved.
Themes and this block both match
<html>and both live in@layer base, sohtml[data-high-contrast="true"](0,1,1) wins over[data-theme="…"](0,1,0) andreplaced each theme's good value with nothing.
Measured on a running instance (
midnight-cinema, Chrome), reading computed valuesoff
document.documentElementwith high contrast on: all seven self-referencingtokens computed empty (
--border --input --surface --surface-hover --surface-raised --accent --muted-foreground), while the non-self-referencing--foregroundand--ambient-glow-opacityapplied correctly. The split fallsexactly along the self-reference line.
Two visible consequences, both making high contrast worse than standard mode:
--surfaceinvalid, so.surface-panel/.surface-panel-subtle/.surface-panel-raisedcomputedbackground-color: rgba(0, 0, 0, 0)and rendered transparent.border-colorfell back tocurrentColor,and the block sets
--foreground: #ffffff, so borders renderedrgb(255, 255, 255)instead ofrgb(40, 40, 46).git log -Ltraces the block unchanged to c085b12, so this never worked. It likelywent unreported because any profile with a stored
ui.custom_theme_varsoverridenever sees it: those are injected unlayered by
CustomThemeProviderand win overthis block.
Second defect, found in review. Every override mixed toward hard-coded white,
which raises contrast on a dark theme and destroys it on a light one. Computed
against cinema-light's
#f4f4f6page:--muted-foreground--foreground#ffffffon#f4f4f6)The accessibility mode drove body text to near-invisible on that theme. The
--foregroundhalf was already live before this PR, since it never self-referenced;repairing the cycle would have activated the rest.
Approach
The cycle. The mix needs an input that is not the property being assigned. Each
theme defines the literal under
--<token>-base, the semantic token is an alias,and high contrast mixes from the base.
Three shapes were tried in a browser; only the base token works:
C is worth recording because it is the intuitive fix and does not work.
The alternative — dropping
color-mixand hardcoding a lightened value per theme —also works, but it is 7 × 5 hand-computed literals that drift as themes change.
The direction. Each theme declares
--contrast-boost— white on the four darkthemes, black on cinema-light — and every override mixes toward that. On
cinema-light this yields 15.49:1 for muted text and 19.12:1 for body text. Dark
themes are unchanged except
--ring, which moves fromoklch(0.95 0 0)to theboost: negligible there, and the difference between a visible and an invisible focus
ring on the light theme.
:rootdefaults the boost to white so a theme that omitsit degrades to the previous behaviour rather than to an invalid value.
Validation
The 5 failures are pre-existing and unrelated:
PersonDetail > formatBirthDate×3,SectionItemCard > renders premiere metadata,CardOverlays > scales legacy browsers. I reran those three files against a cleanmainand got the identical 5;they look locale/timezone dependent.
Compiled output loaded into a real document root: all seven tokens resolve with high
contrast both off and on. No self-referencing declaration remains anywhere under
web/src.Two suites, both mutation-checked rather than assumed:
highContrastCss.test.ts— fails the whole stylesheet on any self-referencingcustom property, checks the mix, the aliases, and that every theme defines every
base token. Reintroducing the old declaration fails 2 of 4.
highContrastContrast.test.ts— computed WCAG ratios per theme: the boost mustcontrast with its own page, body text must clear AA, and neither muted text nor
borders may come out worse in high contrast than without it. Reverting
cinema-light to boosting toward white fails 4 of 20. Asserting the declarations
merely exist could never have caught the direction bug — the tokens were all
present and correct-looking.
UI evidence not attached. The visible change is a theme-wide colour shift behind
an accessibility toggle; I can attach before/after captures per theme if that is
required before merge.
Risks
--<token>-baseis introduced for seven tokens across fivethemes. Anything outside
app.cssreferencing those seven names directly wouldneed updating; nothing does, and the semantic names are unchanged for consumers.
--ringon dark themes shifts fromoklch(0.95 0 0)to#ffffffin highcontrast only. Called out above rather than buried.
Checklist
AI Disclosure
AI-authored and human-verified. The bug was found while diagnosing an unrelated
theming problem on a live instance.
rather than reasoned about, which is how the plausible-but-wrong descendant-element
fix was rejected. Review findings on this PR — the light-theme contrast inversion
and two
tscerrors in the test added by the first commit — were reproduced andquantified against the code before being fixed in the second commit. I had not run
tsc -bon this branch before opening the PR;vite builddoes not typecheck,which is why the errors were not caught earlier.