BUG: html repr not legible in dark themes

[martinfleis]

Our HTML repr works only in light IDE themes like the default JLab. Dark mode makes it illegible.

[benbovy]

Since you have been inspired by xarray for this repr, I just want to mention the following PRs in case you haven't checked it yet:

• jupyterlab dark theme pydata/xarray#3443
• support darkmode pydata/xarray#4036
• Fix lag in Jupyter caused by CSS in _repr_html_ pydata/xarray#5201

(more off-topic: I also like the recently added reprs for dask clusters and clients, e.g., dask/distributed#4857)

[martinfleis]

@benbovy thanks a lot for the references! It looks like a lot of fun ahead.