Theme Slack Desktop

ssb-interop.js

// Append to the bottom of /usr/lib/slack/resources/app.asar.unpacked/src/static/ssb-interop.js
document.addEventListener('DOMContentLoaded', function() {
 $.ajax({
   // Your CSS here.
   url: 'https://raw.githubusercontent.com/laCour/slack-night-mode/master/css/raw/black.css',
   success: function(css) {
     $("<style></style>").appendTo('head').html(css);
   }
 });
});