Greasy Fork is available in English.
Generate table of contents for any website. By default, it is not open. You need to go to the plug-in menu to open the switch for the website that wants to open the toc. The plug-in will remember this switch, and the toc will be generated automatically according to the switch when you open the website the next time.
Personally, I liked the collapse version more than the dim version. It feels less intrusively, as it doesn't overlap visually and doesn't block clicking.