Can not change custom.css on user pods through Dockerfile

I am deploying jupyterhub by k8.
I would like to customize the jupyterhub.
In order to do that I build a dockerfile.
The problem is I can not find the directory I create or the package I install or else the custom.css which I upload by docker in the pod when user is created.

RUN mkdir -p /home/$NB_USER/.jupyter/custom/

RUN pip install jupyterthemes

RUN jt -t onedork -fs 95 -altp -tfs 11 -nfs 115 -cellw 88% -T -N

COPY --chown=$NB_UID:$NB_GID ./customnew.css /home/$NB_USER/.jupyter/custom/custom.css

config.yaml :

#uid: 0
#fsGid: 0
# Get the latest image tag at:
# Docker Hub
# Inspect the Dockerfile at:
# docker-stacks/Dockerfile at master · jupyter/docker-stacks · GitHub
name: aads/jupyterhub-test
tag: latest


The configuration of your singleuser server is more or less independent of JupyterHub. This should make it easier to investigate- you can just run your Docker container locally instead of deploying it to Kubernetes.

If you give us more details about what you’re trying to do, and which interface you’re using (e.g. JupyterLab, Notebook) someone more familiar with the application might be able to help.

Thank you for your answer. I can run the Docker container locally. It works.
I am trying to customize jupyterhub. For this, I begin changing custom.css. Black bakground, font changes etc.

The JupyterHub container and the singleuser containers are separate. If you want to modify the JupyterHub interface you’ll need to modify the JupyterHub container.

I already modified login page of jupyterhub.
What I want to do now is modifying custom.css of the notebook.
I try to do it by docker for singleuser by copyting a custom.css file .
But it seems after my image is called my changes are overwritten.

For anyone having the same problem I solved this problem by config.yaml

command: [“jt”,"-t",“onedork”,"-fs",“95”, “-altp”, “-tfs”, “11”, “-nfs”, “115”, “-cellw”, “88%”, “-T”, “-N”]