enable_default_pandas_dataframe_styling to enable dark mode

[timvink]

Hi @greenape, great plugin and super useful !

I'm using mkdocs-material theme with this plugin, setting enable_default_pandas_dataframe_styling: true. Works and looks great in light mode, but in dark mode (recently introduced in mkdocs-material) it does not render nicely:

This can be solved by using the CSS prefers-color-scheme media feature, basically adding a

@media (prefers-color-scheme: dark) {
   ...
}

section to mknotebooks/templates/pandas-dataframe.css. This is the same way how mkdocs-material implemented their dark mode).

I'd also be willing to give a PR try if you want, let me know!