Styled editor settings subsections links

[elig0n]

Description

The "Styled editor" Settings page is quite long and has several sections that I believe can be linked from the left-side navigation menu using i.e. DOM elements IDs.
I.e similar to the way the Settings and Menu editor root sections has indented sub-sections links in the navigation menu at the left.

This way navigation to specific CSS settings subsections gets quicker and easier.