Supported by Firefox and Chrome and gives the developer more control over CSS cascading. This would be helpful when when writing components that get inserted in other environments.
Preferably both property: initial and all: initial would be supported.
The initial and unset CSS wide values are already in development in Microsoft Edge. The all shorthand property is now on the backlog with a priority of medium. You can track status updates at https://dev.modern.ie/platform/status/cssallshorthand/
David Storey [MSFT] commented
There is also the `unset` CSS wide value.