Re: [csswg-drafts] [css-borders] allow multiple borders (#13044)

From the perspective of someone who uses CSS, I'd really just like multiple borders to be just that - multiple borders applied, in order, each one outside the previous one.

i.e., I'd like something like this:

```html
<div style="border: 1px solid red, 1px solid blue">Hello!</div>
```

to have the same appearance as this:

```html
<div style="border: 1px solid blue"><div style="border: 1px solid red">Hello!</div></div>
```

I don't personally see any confusion caused by "listifying" the `border-color` properties. Instead, I think it is important that the way you specify colours matches up with the other properties, e.g. if you have:

```css
.fancy-border {
  border-width: 2px, 4px;
  border-color: blue red red blue, yellow green green yellow;
}
```
Then you can see that the blue and red border is the 2px thick one, and the yellow and green border is the 4px thick one.

I don't think adding or remove a border of an existing element on a page is something which needs any special consideration. In general, people should *not* be doing that, since doing so (unless you're careful to maintain total border width) would re-layout the page. CSS authors can use custom properties to make it more ergonomic to alter colors/styles of existing borders without re-specifying the entire border set. 

A benefit of having native multiple border support is that people will be more likely to use `outline` for its intended purpose of adding a transient indication of focus/selection/attention. Additionally, if there is a reasonable "multiple border" syntax, the outline syntax could be extended in the same way to allow someone to e.g. create a black/white focus ring via outline which has high contrast over arbitrary backgrounds.


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Received on Monday, 17 November 2025 17:36:38 UTC