<div class="ballon"></div>

.balloon{

         width: 160px;

         height: 160px;

         background: #faf9f9;

          /*css3 圆角属性*/

          border-radius: 50% 50% 25% 50%;

           /*顺时针旋转45度*/

           transform: rotate(45deg);

           /*盒子阴影 x位移 y位移 羽化 半径 颜色 */

           box-shadow: -8px -8px 80px -8px #873940 inset;

}

/*after  before 伪元素*/

.balloon::after{

           position: absolute;

            bottom: 5px;

            right: 5px;

            content:"";

             display: block;

             /*width: 18px;

             height: 18px;*/

             /*background: #873940;*/

            /*transform: rotate(45deg);*/

             border: 8px solid transparent;

             border-right-color: #873940;

             transform: rotate(45deg);

             border-radius: 50%;

}