// ==UserScript==
// @name _TeX SE, Swap header background
// @match *://tex.stackexchange.com/*
// @grant GM_addStyle
// @run-at document-start
// ==/UserScript==
GM_addStyle ( `
#header {
background: transparent url('https://i.stack.imgur.com/LVfSC.png') no-repeat 50% -25px !important;
}
` );