SE Banner Fixer

// ==UserScript==
// @name           SE Banner Fixer
// @namespace      https://gist.github.com/WiredUK
// @description    Fix banner to top of window
// @include        http://*.stackexchange.com/*
// @include        http://superuser.com/*
// @include        http://serverfault.com/*
// @include        http://meta.stackoverflow.com/*
// @include        http://stackoverflow.com/*
// @include        http://stackapps.com/*
// ==/UserScript==

$('.topbar').css("position", "fixed");
$('.topbar').css("z-index", "100");
$('.container').css("padding-top", "20px");

Shamefully stolen (and adapted) from a script on StackApps written by Fosco