@property

Acceptable Support Updated: Dec 17, 2025

Allows for property type checking and constraining, setting default values, and defining whether or not a custom property can inherit values.

Baseline:
Newly
Functional:
Critical
Usage:
Light DOM Priority

Per current browser support, @property definitions can only exist in light DOM. However, applied defined properties in shadow DOM respect those definitions. This makes them usable for applications that are able to host a global stylesheet.

Shadow DOM Related Issues

@property registration within shadow DOM

Discussion has reopened on making @property registrations in shadow DOM globally available, as the previous resolution wasn’t implemented.

May Change
Web Platform Test
Chrome 147
Edge 146
Firefox 149
Safari 26.4
@property rules in shadow trees should be globally registered
fail
fail
fail
fail
WPT sources: at-property-shadow