I have created this style for Envato Forums. it’s just manipulating the DOM.
Here is how it looks like :
IMAGE LINK (new users can’t put images)
Actual Code to Install : Envato : Old Forum Style for New Forums · GitHub
I’m new to Discourse. I’d love to know how this can be integrated in “Site Customization”
sam
(Sam Saffron)
2
Link is broken, do you have a local discourse install or one where you are an admin ?
erlend_sh
(Erlend Sogge Heggen)
3
sam
(Sam Saffron)
4
Sorry, I mean the gist link is broken.
simon
5
You might get some ideas for how to include a thumbnail image from this post: Reddit Style picture thumbnail on the left
Sorry, here is the actual link to the CSS & JS Code
Oops… cant post more than two link
please see the original post for the updated link 
riking
(Kane York)
7
observeDOM( document.getElementById('main-outlet') ,function(){
setTimeout(function(){
$('.topic-list-item').not('.old-forum-loaded').each(function() {
showAvatars( $(this) );
hideCustomTags( $(this) );
});
},1000)
});
You should be hooking into Ember to do these
That’ll let you filter out the tags before they even go into the DOM.
I wish I could. but I’m new to the Ember thing 