Which custom.css to modify in ltjh installation?

JupyterHub
1

Which is the right custom.css to modify for ltjh installation on Ubuntu 18.04?

sudo find . -name 'custom.css' -exec ls -lah {} \;
-rw-rw-r-- 2 root root 135 May  7 21:35 ./opt/tljh/user/lib/python3.7/site-packages/notebook/static/custom/custom.css
-rw-rw-r-- 2 root root 144 Mar 13  2020 ./opt/tljh/user/lib/python3.7/site-packages/jupyter_core/tests/dotipython/profile_default/static/custom/custom.cs
-rw-rw-r-- 2 root root 144 Mar 13  2020 ./opt/tljh/user/lib/python3.7/site-packages/jupyter_core/tests/dotipython_empty/profile_default/static/custom/cus
.css
-rw-rw-r-- 2 root root 144 Mar 13  2020 ./opt/tljh/user/pkgs/jupyter_core-4.6.3-py37hc8dfbb8_1/lib/python3.7/site-packages/jupyter_core/tests/dotipython/
file_default/static/custom/custom.css
-rw-rw-r-- 2 root root 144 Mar 13  2020 ./opt/tljh/user/pkgs/jupyter_core-4.6.3-py37hc8dfbb8_1/lib/python3.7/site-packages/jupyter_core/tests/dotipython_
ty/profile_default/static/custom/custom.css
-rw-rw-r-- 2 root root 135 May  7 21:35 ./opt/tljh/user/pkgs/notebook-6.0.3-py37hc8dfbb8_0/lib/python3.7/site-packages/notebook/static/custom/custom.css

Use case: I want to add a Google font import so I can use it in Jupyter. I first tried using a local import inside notebook but it does nothing.

This code cell in notebook does not work(no call to Googleapis is made in Network):

%%html
<style>
<link href="https://fonts.googleapis.com/css2?family=Poppins:wght@100;200;300;400;500;600;700;800;900&display=swap" rel="stylesheet">
</style>
2

Well figured by trial and error but unsure if this is the canonical place.

So modifying ./opt/tljh/user/lib/python3.7/site-packages/notebook/static/custom/custom.css works

Updating Python should lead to a different path.