修改placeholder样式

 /* 修改placeholder样式，兼容性 新版火狐，IE10+ */
         .login-input::-webkit-input-placeholder {
             color: #000;
             font-size: 0.3rem;
             transition: .5s;
             transform-origin: left top;
         }
         .login-input::-moz-placeholder {
             color: #000;
             font-size: 0.3rem;
             transition: .5s;
             transform-origin: left top;
         }
         .login-input:-ms-input-placeholder {
             color: #000;
             font-size: 0.3rem;
             transition: .5s;
             transform-origin: left top;
         }
         /* 兼容性 新版火狐，IE10+ */
         .login-input:focus::-webkit-input-placeholder {
             color: #aaa;
             transform: scale(0.7) translateY(-0.28rem);
         }
         .login-input:focus::-moz-placeholder {
             color: #aaa;
             transform: scale(0.7) translateY(-0.28rem);
         }
         .login-input:focus:-ms-input-placeholder {
             color: #aaa;
             transform: scale(0.7) translateY(-0.28rem);
         }