//add   addCssRule('.bcd',{'color':'red','font-weight':'bold','font-size':'12px'},document.styleSheets[1]);

     function addCssRule(selector,styles,styleSheet,index){

         var sheets = styleSheet instanceof Array ? styleSheet : [styleSheet],

             style = '',

             declaration = '';

         for(var pro in styles){

             if(styles.hasOwnProperty(pro)){

                 declaration += (pro + ':' + styles[pro] + ';');

             }

         }

         style = selector + '{' + declaration + '}';

         for(var i = 0,j = sheets.length; i < j;i++){

             if(sheets[i].insertRule){

                 index = index >= 0 ? index : sheets[i]['cssRules'].length;

                 sheets[i].insertRule(style,index);

             }else if(sheets[i].addRule){  //IE

                 index = index >= 0 ? index : -1;  //-1为末尾

                 sheets[i].addRule(selector,declaration,index);

             }

         }

     }

     //modify   editCssRule('.abc',{'font-weight':'bold','font-size':'14px'},document.styleSheets[1]);

     function editCssRule(selector,styles,styleSheet){

         var sheets = styleSheet instanceof Array ? styleSheet : [styleSheet];

         selector = selector.toUpperCase(); // ie9以下标签选择器默认是大写   这里统一下

         //对大小写敏感的selector 会有问题

         for(var i = 0,j = sheets.length; i < j;i++){

             var rules = sheets[i]['cssRules'] || sheets[i]['rules'];   //ie为 rules

             if(!rules){ continue;}

             for(var m = 0,n = rules.length;m < n;m++){

                 if(rules[m]['selectorText'].toUpperCase() == selector){

                     for(var pro in styles){

                         if(styles.hasOwnProperty(pro)){

                             rules[m].style[cssCamilize(pro)] = styles[pro];

                         }

                     }

                 }

             }

         }

     }

     //del   delCssRule('.bcd',document.styleSheets[1]);

     function delCssRule(selector,styleSheet,index){

         var sheets = styleSheet instanceof Array ? styleSheet : [styleSheet];

         selector = selector.toUpperCase();

         for(var i = 0,j = sheets.length; i < j;i++){

             var rules = sheets[i]['cssRules'] || sheets[i]['rules'];   //ie为 rules

             if(index >=0 && index < rules.length){

                 sheets[i].deleteRule ? sheets[i].deleteRule(index) : sheets[i].removeRule(index);

             }else if(selector){

                for(var m = 0,n = rules.length;m < n;m++){

                     if(rules[m]['selectorText'].toUpperCase() == selector){

                        sheets[i].deleteRule ? sheets[i].deleteRule(m) : sheets[i].removeRule(m);;  //可能存在多个一样的selector  全部删除

                     }

                 }

             }else{

                 return false;

             }

         }

     };

 function cssCamilize(str){

         return str.replace(/-(\w)/g,function($1,$2){

             return $2.toUpperCase();

         });

     };

//参考：http://www.cnblogs.com/2050/p/4029656.html

function addCSS(cssText){

    var style = document.createElement('style'),  //创建一个style元素

        head = document.head || document.getElementsByTagName('head')[0]; //获取head元素

    style.type = 'text/css'; //这里必须显示设置style元素的type属性为text/css，否则在ie中不起作用

    if(style.styleSheet){ //IE

        var func = function(){

            try{ //防止IE中stylesheet数量超过限制而发生错误

                style.styleSheet.cssText = cssText;

            }catch(e){

            }

        }

        //如果当前styleSheet还不能用，则放到异步中则行

        if(style.styleSheet.disabled){

            setTimeout(func,10);

        }else{

            func();

        }

    }else{ //w3c

        //w3c浏览器中只要创建文本节点插入到style元素中就行了

        var textNode = document.createTextNode(cssText);

        style.appendChild(textNode);

    }

    head.appendChild(style); //把创建的style元素插入到head中

}