[css-transitions] clarify that the all keyword used in transition-property applies to custom properties #8456
Description
The all keyword used in the transition-property property is defined as such:
the keyword
all[…] indicates that all properties are to be transitioned.
I think it would help to explicitly call out that all properties includes custom properties. As of this writing, Chrome does not transition registered custom properties when transition-property: all is used, and Safari does not either although WebKit/WebKit#10142 will correct this.
I think it would be useful to clarify as well to clearly distinguish with the all property which specifically calls out that it excludes custom properties:
The all property is a shorthand that resets all CSS properties except direction and unicode-bidi. It only accepts the CSS-wide keywords. It does not reset custom properties [css-variables-1].