Autoprefixer 9.5 brings mask-composite
support.
a {
mask-composite: add;
}
b {
mask: url(intersect.png) intersect, url(exclude.png);
}
a {
-webkit-mask-composite: source-over;
mask-composite: add;
}
b {
-webkit-mask: url(intersect.png), url(exclude.png);
-webkit-mask-composite: source-in, xor;
mask: url(intersect.png) intersect, url(exclude.png);
}
Thanks to @semeleven for implementation and @iamvdo for suggestion.