Fix server push and use Link header to load CSS

Nginx with http2_push_preload on will convert the Link header to server
pushes, so we use it to load css.

README.md

@@ -49,6 +49,7 @@ For [docker](https://hub.docker.com/repository/docker/hrfee/jfa-go), run:
 docker create \
              --name "jfa-go" \ # Whatever you want to name it
              -p 8056:8056 \
+            # -p 8057:8057 if using tls
              -v /path/to/.config/jfa-go:/data \ # Path to wherever you want to store the config file and other data
              -v /path/to/jellyfin:/jf \ # Path to jellyfin config directory
              -v /etc/localtime:/etc/localtime:ro \ # Makes sure time is correct