UserScript/GithubFullWidth

gihub-fullwidth.user.js

// ==UserScript==
// @name       Github Full Width
// @namespace  github.responsive.width
// @version    0.1
// @description make github use all your screen
// @include    https://github.com/*/blob/*
// @include    https://github.com/*/pull/*/files
// @include    https://github.com/*/commit/*
// @copyright  2013+, Benjamin Eidelman
// ==/UserScript==

var style = document.createElement('style');
style.setAttribute('type', 'text/css');
style.innerHTML = '\
.container {\
  width: 98%;\
}\
#slider .frames {\
  width: 100%;\
}\
#slider .frames .frame {\
  width: 100%;\
}'
document.body.appendChild(style);

works on Chrome on OSX too

Also GreaseMonkey on FF

nice, thx!