Sidebar Size
If you choose to display a sidebar on your page, it is possible to choose from two different sizes. By default, the sidebar will take up 1/3 of screen width on desktop. You can, however, choose to make it more compact. Go to Appearance > Customize > General Settings, and toggle the COMPACT setting to shrink the sidebar to 1/4 of the screen width.
Click here to view a demo of the compact sidebar.