I want to be able to define and change all my notebook's styles globally. I therefore want to create a new stylesheet notebook. It seems like something that should be easy to do for simple modifications from the default stylesheet. But I have not found anything telling me how to do it.
How can I create my own stylesheet notebook, and use it for all the notbooks in my project?
Will changes to that stylesheet show up in my notebooks after I have already chosen it for that notebook?
I am not asking how to modify the private style sheet of a notebook.