Thanks. We put a temporary fix in place and working on a permanent solution.
Just don't use his board. If I have to guess he generates traffic via proxies to inflate poster numbers so the board looks active.

Beside that what users can do is to disable custom css even before it loads. Use Greasemonkey or similar.
Include the board (on all domains), like this:

// @include https://endchan.gg/ashIeyj/*

and use:

document.querySelector("title").nextElementSibling.href = "";