You can try Access WebAdmin>Virtual Hosts>Context
Create a type and URl you want with Extra Headers: Access-Control-Allow-Origin *
Restart lsws gracefully
Then you can see Response Headers like this:
- Accept-Ranges: bytes
- Access-Control-Allow-Origin: *
- Cache-Control: public, max-age=604800
- Connection: Keep-Alive
- Content-Length: 0
- Content-Type: text/css
- Date: Mon, 02 Oct 2017 17:52:37 GMT
- Etag: "0-59d265d1-f2e9"
- Expires: Mon, 09 Oct 2017 17:52:37 GMT
- Last-Modified: Mon, 02 Oct 2017 16:14:09 GMT
- Server: LiteSpeed