I'm using Sass for styles. When i try to compile this part of code: 

```
.heart {
  width: $size * 2;
  height: $size * 1.65;
  cursor: pointer;

  &:before {
    position: absolute;
    content: "";
    left: $size;
    width: $size;
    height: $size * 1.65;
    background: #fff;
    border-radius: 50px 50px 0 0;
    transform: rotate(-45deg);
    transform-origin: 0 100%;
  }
  &:after {
    @extend .heart:before;
    left: 0;
    transform: rotate(45deg);
    transform-origin :100% 100%;
  }
}

```

I got this message: 

```
@extend .heart:before;
Error: compound selectors may longer be extended.
Consider `@extend .heart, :before` instead.
See http://sass-lang.com/documentation/file.SASS_REFERENCE.html#extending_compound_selectors for details.

@extend .heart:before;

```

It doesn't compile with terminal, but it's compile and works as expected with Prepros application. Any ideas why it doesn't work when i try to compile with `sass` command? 

I used this example: <https://codepen.io/souporserious/pen/yEntv>