QUOTE(Shank @ Dec 24 2021, 02:34)

I didn't do it in the method you wanted, so this may not be what you want, but I replied to your helpdesk thread on this with a potential solution
Worth noting, you can also just throw the css part onto something like stylus and it'll work just as well
Finally got round to fixing
CODE
// ==UserScript==
// @name Gif Highlighter
// @include https://e-hentai.org/g/*
// @version 1.0.0
// @author Shank
// @grant GM_addStyle
// @run-at document-start
// ==/UserScript==
GM_addStyle ( `
div[title$="gif"] {border: 5px solid red!important;}
div[title$="png"] {border: 5px solid green!important;}
div[title$="webp"] {border: 5px solid orange!important;}
div[title$="jpg"] {border: 5px solid green!important;}
` );
png/jpg highlight green, gif red, webp orange. Easy enough to change to whatever.
This is useful for highlighting the different format types, for locating and checking pages quickly, (and side benefit of, it sometimes let you spot files that have been modified and saved in a different format, if jpg or png are changed to unique colours), but for something that counts .gif , terry has a script
https://forums.e-hentai.org/index.php?showtopic=276004