book theme - remove left sidebar completely

[Rob Torop]

When I use this theme, I always tell people to click the 3 lines at the top of the middle pane so as to remove the large sidebar on the left.  I know how what to put in conf.py to make the sidebar be *empty*, but I want to remove it completely so that more of screen can be occupied by text.

Is there a way to do it that doesn't involve fiddling with css,etc?  Or at least make it much narrower?