Use less.js in development mode with watch (auto-reload) enabled

less.html

<link rel="stylesheet/less" type="text/css" href="styles.less">
<script type="text/javascript">
	/* Put Less in development mode */
	less = {};
	less.env = 'development';
</script>
<script src="less.js"></script>
<script type="text/javascript">
	/* Enable Less auto reloading */
	less.watch();
</script>