<===> input.scss
.simple-value {
  // A custom property at the end of a style rule doesn't need a semicolon.
  --without-semicolon: value
}

.bracketed-value {
  --without-semicolon: {
    a: b
  }
}

<===> output.css
.simple-value {
  --without-semicolon: value ;
}

.bracketed-value {
  --without-semicolon: {
    a: b
  } ;
}

<===> output-libsass.css
.simple-value {
  --without-semicolon: value
;
}

.bracketed-value {
  --without-semicolon: {
    a: b
  }
;
}