var el="cimg";
	  var bgimg=new Array("center_img/img_c01.jpg", "center_img/img_c02.jpg", "center_img/img_c03.jpg", "center_img/img_c04.jpg", "center_img/img_c05.jpg", "center_img/img_c06.jpg", "center_img/img_c07.jpg", "center_img/img_c08.jpg", "center_img/img_c09.jpg", "center_img/img_c10.jpg");
	  var random=Math.round((bgimg.length-1)*Math.random());
	  var cssStr="#"+el+" { background: url("+bgimg[random]+") no-repeat top left } ";
	  var style=document.createElement("style");style.setAttribute("type","text/css");
	    if(style.styleSheet){style.styleSheet.cssText=cssStr;}
	    else{
	      var cssText=document.createTextNode(cssStr);style.appendChild(cssText);}document.getElementsByTagName("head")[0].appendChild(style);