登陆页面问题(wnf管理平台)

1.验证码(随机数)

//获取验证码
var random;
function codeImg () {
   random=Math.random();
    var $codeImg = $(".code_img");
   var rad="https://services.torld.com/advertiser_forward/service?service=tor.code&rm="+random;
   $codeImg.attr("src", rad);
}
codeImg();


2.登陆//登录    

$(".btn").click(function () {
   //用户名
   var $username = $(".userName").val(),
       $password = $(".password").val(),
       $code = $(".code").val();
   

   
   //登录接口
   common.ajax({
      data:{
         service: "tor.login",
         username: $username,
         passwd: md5($password),
         checkcode: $code,
         rm: random
      },
      fail:function(re){
         codeImg();
      },
      success: function (re) {
         
         $.cookie("login_token", re.token);

         sessionStorage.setItem("menu", JSON.stringify(re));
         
         sessionStorage.setItem("username", $username);
         
         location.href = "common.html";
         
      }
   });
});

3.width

//在图片收缩的同时,保持在页面居中显示
 -webkit-fit-content;
 -moz-fit-content;
 -ms-fit-content;
 -0-fit-content;