Nested CSS @apply mixins are breaking when minified.

I’ve run into a problem after CSS has been minified (through kangax/html-minifier which uses clean-css) where the last property being applied to a CSS mixin variable loses its semi-colon. If this property is another mixin, it breaks, particularly for IE11 and Edge. Could this please be fixed so that the semi-colons are preserved?

As a side note, I’ve found a way around this by adding another property, but it gets messy, so if this could be fixed, it would be greatly appreciated.

Input CSS

--my-mixin: {
    @apply --another-mixin;
};

Actual output CSS

--my-mixin:{@apply --another-mixin};

Expected output CSS

--my-mixin:{@apply --another-mixin;};

[jakubpawlowicz]

The fix is out in 3.4.26 and 4.1.2.

[Norman-Amy]

I’m using it in Polymer web components. I believe Polymer provides a shim for browsers when it isn’t supported natively.