var count = 0;

	var themes = new Array(4);
	themes[0] = 'style.bg-grey.css';
	themes[1] = 'style.bg-blue.css';
	themes[2] = 'style.bg-black.css';
	themes[3] = 'style.bg-grey-blue.css';

	function switch_bg(id, path) {
		if(count < 3) {
			count = count + 1;
		}else{
			count = 0;
		}
		
		//configure style directory
		var path = path + themes[count];

		document.getElementById(id).href = path;
	}

	function switch_theme(id, theme, path) {
		//configure style directory
		var path = path + theme;

		//load stylesheet
		document.getElementById(id).href = path;
	}