See the FIXME in TreeResolver::createAnimatedElementUpdate():

            // The cascade may override animated properties and have dependencies to them.
            // FIXME: This is wrong if there are both transitions and animations running on the same element.
            applyCascadeAfterAnimation(*animatedStyle, animatedProperties, styleable.hasRunningTransitions(), *resolvedStyle.matchResult, element, resolutionContext);

We should handle transitions and animations separately.