CSS to add un-selectable line numbers to your github gists
.gist .highlight {
border-left: 3ex solid #eee;
position: relative;
}
.gist .highlight pre { counter-reset: linenumbers; }
.gist .highlight pre div:before {
color: #aaa;
content: counter(linenumbers);
counter-increment: linenumbers;
left: -4ex;
position: absolute;
text-align: right;
width: 3.0ex;
-webkit-touch-callout: none;
-webkit-user-select: none;
-khtml-user-select: none;
-moz-user-select: none;
-ms-user-select: none;
user-select: none;
}