Re: [csswg-drafts] [css-text-decor-5] Allow percentages in `text-decoration-trim` (#8403)

I agree that this may not block shipping, though it would still be nice if we could resolve on a proper behavior.

So, I imagine [my proposal](https://github.com/w3c/csswg-drafts/issues/8403#issuecomment-3396895682) to render like in the following examples:

One-value case:

```
data:text/html,<p style="width:10em;font-size:3em;">This is a text including
<span style="text-decoration:0.1em underline;text-underline-offset:0.25em;
text-decoration-trim:10%;">some underlined part that wraps</span>
into two lines.</p>
```

would render like this:

<img width="240" height="112" alt="Rendering of text-decoration-trim with a single value of 10%" src="https://github.com/user-attachments/assets/8baa857e-1ccb-45fe-8904-1c3fb7c19213" />

Two-value case:

```
data:text/html,<p style="width:10em;font-size:3em;">This is a text including
<span style="text-decoration:0.1em underline;text-underline-offset:0.25em;
text-decoration-trim:0 20%;">some underlined part that wraps</span>
into two lines.</p>
```

<img width="240" height="112" alt="Rendering of text-decoration-trim with two values, the first one 0, the second one 20%" src="https://github.com/user-attachments/assets/5268abee-1098-41b9-8820-235ca145a6cd" />

`box-decoration-break` set to `clone`:

```
data:text/html,<p style="width:10em;font-size:3em;">This is a text including
<span style="text-decoration:0.1em underline;text-underline-offset:0.25em;
text-decoration-trim:5%;box-decoration-break:clone;">some underlined part that wraps</span>
into two lines.</p>
```

<img width="240" height="112" alt="Rendering of text-decoration-trim with a single value of 10% and box-decoration-break set to clone" src="https://github.com/user-attachments/assets/cb64a656-a065-448d-8d81-a703dd30a477" />

So given that, maybe we can get a resolution. So adding this to the agenda.

-----

What has to be discussed before shipping are #8402 and #12947.

Sebastian

-- 
GitHub Notification of comment by SebastianZ
Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/8403#issuecomment-3448944643 using your GitHub account


-- 
Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config

Received on Sunday, 26 October 2025 21:41:02 UTC