[csswg-drafts] [css-ui] Proposal: Allow `outline-offset` to reflect the effective offset for `outline-style: auto` (#13587)

sb3nder has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-ui] Proposal: Allow `outline-offset` to reflect the effective offset for `outline-style: auto` ==
## Problem

When `outline-style: auto` is used, browsers apply a UA-specific visual offset, and when `outline-offset` is used its value is summed to that UA-specific offset, because the initial value of `outline-offset` is `0px`.
**(effective offset = specified outline-offset + UA internal auto offset)**

As a result, explicitly specified offsets may not correspond to the effective rendered offset, and results are much different between UAs.

Current effective offset, with `outline-style: auto` and `outline-offset: 0px`:

- Chrome: -1.5px
- Firefox: 0px
- WebKit: 2px

Or with `outline-offset: 2px`:

- Chrome: 0.5px
- Firefox: 2px
- WebKit: 4px

## Solution

Change `outline-offset` initial value to `auto`:

- When `outline-style` is not `auto`, `outline-offset: auto` computes to `0px`
- When `outline-style: auto` and `outline-offset: auto`, `getComputedStyle().outlineOffset` returns `0px` to avoid fingerprinting

This would allow UAs to interpret `outline-offset` as the effective rendered offset
**(effective offset = specified outline-offset)**

This would allow developers to rely on `outline-offset` for style auto focus rings, especially in scenarios involving overflow.

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/13587 using your GitHub account


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Received on Tuesday, 3 March 2026 14:22:51 UTC