A dark Jupyter/iPython notebook theme.
Put the custom.css file in the folder ~/.ipython/profile_default/static/custom/.
You probable have to create the static and custom folders.
Jupyter got updated, the new location for the custom.css is ~/.jupyter/custom/custom.css.
You have to create the custom folder.
If you hover over the Python logo the menus slide down.
Notebooks used in screenshots: Alternatives to Matplotlib Pandas Cleaning Data