WPT details: https://wpt.fyi/css/css-properties-values-api/animation/custom-property-animation-list-type-mismatch.html https://wpt.fyi/css/css-properties-values-api/animation/custom-property-animation-transform-function.html https://wpt.fyi/css/css-properties-values-api/animation/custom-property-animation-transform-list-multiple-values.html https://wpt.fyi/css/css-properties-values-api/animation/custom-property-animation-transform-list-single-values.html https://wpt.fyi/css/css-properties-values-api/animation/custom-property-transition-transform-function.html https://wpt.fyi/css/css-properties-values-api/animation/custom-property-transition-transform-list.html https://wpt.fyi/css/css-properties-values-api/at-property.html https://wpt.fyi/css/css-properties-values-api/registered-property-computation.html https://wpt.fyi/css/css-properties-values-api/registered-property-initial.html https://wpt.fyi/css/css-properties-values-api/register-property-syntax-parsing.html https://wpt.fyi/css/css-properties-values-api/typedom.html
Supports using the <transform-function> and <transform-list> syntaxes for custom properties registered with @property or registerProperty(). The syntax can be used to restrict values of the custom property to represent transforms. This also makes it possible to use transitions and animations directly on these registered custom properties.