simple table of contents kind of thing for js
named after that legendary Area 11 EP album
a "CDN"'d version is at https://weiss.iscute.ovh/f/52d.js
the script looks for elements with data-blackline attribute
if data-blackline is empty, it assumes the section title should be element's text content
if the found element also has for attribute, it will be used to find (using querySelector) the element that has to be scroll-watched
it's visually terrible but I don't care at the moment
it depends on @michcioperz/no-bullshit-onscreen