theme: increase exander left margin

[sedyh]

Hello, some of my friends and I noticed that the default margins for navigation icons are almost absent, they are quite difficult to access in the desktop version of the page.

1. Is it possible to increase the margin a little?

2. It would also be nice to have a same fixed size for the open and closed sections.

[McShelby]

I agree that this would be preferable, but due to time constraints it is unclear when or even whether I will address this in the future.

[sedyh]

I guess I could try to help with this. It doesn't seem very hard to implement.

[McShelby]

I appreciate your help!

Things to keep in mind: 7.1.0 introduced submenus for the shortcut / Hugo menus. This is not exposed in the exampleSite. Those shortcut menus are shown in a slightly compressed form, which has influence on the placement of the expander. So, this needs to be tested, too.