Fix autofill background mismatch in InputGroup and standalone Input

[pedromenezes1]

When browser autofill kicks in, Chrome applies a forced background color only to the <input> element, but not the surrounding InputGroup container or addons. This creates a visual mismatch where the input is blue-tinted but icons, suffixes, and buttons remain white.

Approach

• Use a box-shadow: inset trick to override Chrome's forced autofill background on all inputs/textareas with a consistent kumo-info-tint at 20% mixed with kumo-control
• Spread the same tint to the InputGroup container and hybrid zone via :has(input:-webkit-autofill)
• Preserve Tailwind's ring on standalone inputs by compositing the inset fill alongside all --tw-*-shadow variables
• Suppress the input border inside InputGroup (container handles it) while keeping it on standalone inputs
• Delay Chrome's forced background-color via transition: background-color 5000s so the box-shadow tint is visible*

*Chrome's stylesheet forces an autofill background-color that renders on top of box-shadow: inset and cannot be overridden by our styles. The transition: background-color 5000s delays it from ever visually taking effect, which is the standard workaround used across design systems.

Preview
https://62cda41f-kumo-docs.design-engineering.workers.dev/components/input-group/#icon
https://62cda41f-kumo-docs.design-engineering.workers.dev/components/input-group/#button
https://62cda41f-kumo-docs.design-engineering.workers.dev/components/input

Before

After

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• Reviews
• bonk has reviewed the change
• automated review not possible because: CSS-only change affecting browser autofill behavior, requires manual visual testing across browsers
• Tests
• Tests included/updated
• Additional testing not necessary because: CSS-only visual fix for browser autofill styling, not testable with unit tests

[pkg-pr-new]

npm i https://pkg.pr.new/@cloudflare/kumo@534

commit: 24b534c

[github-actions]

Docs Preview

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Commit: 24b534c

[github-actions]

Visual Regression Report — 20 changed, 19 unchanged

20 screenshot(s) with visual changes:

Button / Basic

183 px (0.18%) changed

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Button / Loading State

0 px (0%) changed

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Button / Disabled State

117 px (0.12%) changed

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Button / Title

272 px (0.27%) changed

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Dialog / Dialog Basic

114 px (0.11%) changed

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Dialog / Dialog Alert

354 px (0.35%) changed

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Dialog (Open)

0 px (0%) changed

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Select / Select Basic

485 px (0.48%) changed

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Select / Select Sizes

886 px (0.48%) changed

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Select / Select Without Label

105 px (0.1%) changed

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Select / Select With Description

889 px (0.75%) changed

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Select / Select With Error

1,730 px (1.46%) changed

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Select / Select Placeholder

595 px (0.59%) changed

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Select / Select With Tooltip

294 px (0.29%) changed

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Select / Select Custom Rendering

414 px (0.41%) changed

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Select / Select Loading

0 px (0%) changed

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Select / Select Complex

1,090 px (0.92%) changed

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Select / Select Disabled Options

765 px (0.75%) changed

Before	After	Diff

Select / Select Disabled Items

176 px (0.17%) changed

Before	After	Diff

Select (Open)

541 px (0%) changed

Before	After	Diff

19 screenshot(s) unchanged

• Button / Variant: Primary
• Button / Variant: Secondary
• Button / Variant: Ghost
• Button / Variant: Destructive
• Button / Variant: Outline
• Button / Variant: Secondary Destructive
• Button / Sizes
• Button / With Icon
• Button / Icon Only
• Button / Link as Button
• Dialog / Dialog With Actions
• Dialog / Dialog Confirmation
• Dialog / Dialog With Select
• Dialog / Dialog With Combobox
• Dialog / Dialog With Dropdown
• Select / Select Multiple
• Select / Select Grouped
• Select / Select Grouped With Disabled
• Select / Select Long List

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Generated by Kumo Visual Regression

[pedromenezes1]

Safari

Before	After

Firefox

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[pedromenezes1]

/bonk

[ask-bonk]

PR #534 Summary: Fix Autofill Background Mismatch in InputGroup

Overview

This PR fixes visual inconsistencies when browser autofill is active on inputs, where Chrome's forced blue background only applied to the input element but not surrounding icons, suffixes, or buttons in InputGroup containers.

Changes Made

1. .changeset/autofill-input-group.md (Added)

• Changeset declaring a patch-level change for @cloudflare/kumo

2. packages/kumo/src/styles/kumo-binding.css (Added 53 lines)

• Input/textarea autofill styling: Uses a box-shadow: inset trick with 1000px spread to create a consistent background color mixing kumo-info-tint (30%) with kumo-control
• Tailwind shadow compatibility: Composites all --tw-*-shadow variables to preserve rings and other shadow effects
• Chrome background-color delay: transition: background-color 5000s prevents Chrome's forced autofill color from visually appearing
• InputGroup border suppression: Sets border-color: transparent on autofilled inputs inside InputGroup (container handles borders)
• Container tint spreading: Uses :has(input:-webkit-autofill) selector to apply matching background tint to InputGroup containers and hybrid zones (20% mix)

Key Technical Details

• Color values: Input uses 30% tint, container uses 20% tint for proper visual layering
• Browser support: WebKit-based browsers (Chrome, Safari, Edge); Firefox doesn't show autofill styling differences
• Tailwind integration: Shadow variables ensure ring-* utilities still work on autofilled inputs

Verification Evidence

• Manual testing: Safari and Firefox screenshots provided showing consistent appearance
• Visual regression: 9 diffs detected (mostly minor sub-pixel changes on Button, Dialog, Select)
• Preview links: Available for testing at 11c0000f-kumo-docs.design-engineering.workers.dev

Approvals

• ✅ Automated review skipped (CSS-only visual fix, requires manual testing)
• ✅ Tests not needed (visual styling only)
• ⏳ Awaiting bonk review

The implementation follows the standard browser autofill override pattern used across design systems and properly integrates with the Kumo theme token system.

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