CSS: support scope at-rules

```shell
~/x
❯ bat test.css
     File: test.css
   1 @scope (body) {
   2   :scope {
   3     color: red;
   4   }
   5 }

~/x
❯ minify test.css
@scope(body){:scope {
    color: red;
  }
}⏎
```

It probably should be

```css
@scope(body){:scope{color:red;}}
```