//下拉菜单样式        /*查找全部select的下拉菜单*/        function getElemsById(cot_val){            return document.getElementById(cot_val);        }        var sel= getElemsById("c_select");        var wrap= getElemsById("sel_wrap");        var result=wrap.getElementsByTagName("span");        sel.onchange=function(){            var opt=this.getElementsByTagName("option");            var len=opt.length;            for(i=0;i