[css-break] Suggest adding new value to `box-decoration-break` to allow bounding box or a separate property to control the background.

[mattrq]

Regarding https://drafts.csswg.org/css-break/#break-decoration

Propose that a new value "bounds" for box-decoration-break.
"bounds" is a suggestion only, any string that conveys the intent.

The value intends to represent rendering the background-* properties such that they are applied to the bounding box of fragmentation boxes. The rendering would be limited to the fragmentation boxes.

E.g.

The border would be around the joined fragment boxes.

E.g.

Scenario	Example
Background
Background clipped to text which has background fragmentation

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Updated based on comment from @Loirooriol:
This suggestion applies mainly to the background portion of the box-decoration-break, so possibly this belongs as its own property/sub-property. E.g. box-decoration-break-background with values slice, clone, and bounds.

[Loirooriol]

May make sense for backgrounds, but it's not clear to me what should happen with decorations that impact layout, like borders.

[mattrq]

The value makes the most sense for the background, so I have updated the title/description to add a separate property that is specific to the background only.