Board Thread:Support Requests - Designing Your Wiki/@comment-36059927-20180827153841/@comment-9605025-20180827161557

You can read about animated GIFs here. As for the pseudo element, it looks like there is an actual element already placed after the name that they are using. You would need to copy the relevant CSS from their wiki (shown below). You need to use the last CSS rule separately for each image you want to use. You would replace " " with the user's name and "" with the URL to the animated GIF.