@layer support needs to be added

[jogibear9988]

Expected Behaviour

@layer rules should be parsed

Actual Behaviour

they are not parsed, see also: reworkcss#165

Reproduce Scenario (including but not limited to)

var css = require('css');
var obj = css.parse("@layer mylayer {.card {--content-box-flex-grow: 1; display: flex; flex-direction: column; position: relative; width: 100%;} }");
css.stringify(obj);

[jogibear9988]

I can look to work on this

[jogibear9988]

fixed in #97

[holblin]

Thanks a lot for your contribution! Sorry I wasn't able to review and merge earlier. A new version should be available soon on npmjs 👍