All I want is to hide the toolbar by default. Wastes several clicks and a few seconds of setup time every time I give a talk from a notebook.
Put this in .jupyter/custom/custom.js
require(['base/js/namespace', 'jquery'], function(IPython, $) {
$([IPython.events]).on('notebook_loaded.Notebook', function() {
$('#header-container').hide();
$('.header-bar').hide();
$('div#maintoolbar').hide();
IPython.menubar._size_header();
});
});