Install jupyterthemes (https://github.com/dunovank/jupyter-themes)
```
conda install -c conda-forge jupyterthemes
```

Edit **$(python -c 'import jupyterthemes as jt; print(jt.__path__[0]);')/layout/notebook.less**
- remove `div#ipython_notebook { display: none; }`
- change `span.autosave_status { font-size: small; }` (i.e. remove `display: none`)
- add `div.output_area img, div.output_area svg {background-color: wheat}`

Run `jt` to set a dark theme, e.g. `monokai`
```
jt -t monokai -f roboto -fs 11 -ofs 10 -nfs 11 -cursw 2 -cursc r -cellw 95% -T -N -kl
```