CSSHTMLHeaderPreprocessor.style=<name> breaks with 6.x.x

[jaymegordo]

Description

I use --CSSHTMLHeaderPreprocessor.style=solarized-dark for example when exporting a notebook to modify the code syntax highlighting. In >6.0.0 this fails (silently) and only uses the default syntax. I've tested by both completely reinstalling everything in a new venv (still fails), then downgrading to 5.6.1 (works again).

Is there any way to confirm that nbconvert can find the correct pygments styles?

Reproduce

• Create new conda env
• Install ipython and nbconvert
• jupyter nbconvert --to html my_notebook.ipynb --CSSHTMLHeaderPreprocessor.style=solarized-dark (doesnt use this theme's syntax)

Nbconvert version: 6.0.7

jupyter related packages: Name	Version
ipykernel	5.3.4
ipython	7.19.0
ipython_genutils	0.2.0
jinja2	2.11.2
jupyter_client	6.1.11
jupyter_core	4.7.0
jupyter_server	1.2.2
jupyterlab	3.0.5
jupyterlab_pygments	0.1.2
jupyterlab_server	2.1.3
nbclassic	0.2.6
nbclient	0.5.1
nbconvert	6.0.7
nbformat	5.1.2
pygments	2.7.4

[JPinSPACE]

I am experiencing the same issue. When I run nbconvert with different styles and then diff the files there is no difference.

[Vaibhav-Ankolekar]

I got the solution for this after a lot of time This solution contains changing Python Library Files (not recommended) Step 1 : Go to .\Python\Python39\Lib\site-packages\nbconvert\preprocessors Step 2: Open csshtmlheader.py with any text-editor Step 3: In class CSSHTMLHeaderPreprocessor there will be style variable, which will have default_value=JupyterStyle, just change value after = to any style you want but in quotes( inverted commas ) for example : default_value='vs' Step 4: Save the file

Now, you can run the command jupyter nbconvert --to html notebook.ipynb, you do not need to add --CSSHTMLHeaderPreprocessor.style=<name>, because by default it will be given the style you mention in csshtmlheader.py. I don't know why the tag is not working as stated in Jupyter Docs

For available styles run this command: pygmentize -L styles

[finale80]

@RagnosVA your methods works, but obviously hardwire you to a specific style defeating the purpose of the command line option

I opened a PR with a generalised fix https://github.com/jupyter/nbconvert/pull/1548