nginx...

gistfile1.txt

  location / {
    expires $expires;

    if ($cors = "simple") {
      add_header "Access-Control-Allow-Origin" "$http_origin";
    }

    if ($cors = "preflight") {
      add_header "Access-Control-Allow-Origin" "$http_origin";
      add_header "Access-Control-Allow-Methods" "GET, HEAD, POST, OPTIONS";
      add_header "Access-Control-Allow-Headers" "Cache-Control";
      return 204;
    }

    try_files $uri /index.html;
  }