pre.numberSource {
	counter-reset: linenumber;
	position: relative;
}

pre.numberSource span[id] {
	counter-increment: linenumber;
	position: relative;
	padding-left: 4em;
}

pre.numberSource span[id] > a::before {
	content: counter(linenumber);
	position: absolute;
	left: 0;
	width: 3em;
	text-align: right;
	color: #888 !important;
	font-family: monospace;
	user-select: none;
	display: inline-block;
}