实现九宫格布局

       <style>       .container::after{content: "";display: block;clear: both;       }       .box{float: left;width: 32%;padding-bottom: 32%;background-color: red;margin-bottom: 1%;       }       .box:not(:nth-child(3n)){margin-right: 1%;       }   </style>   <div class="container">       <div class="box"></div>       <div class="box"></div>       <div class="box"></div>       <div class="box"></div>       <div class="box"></div>       <div class="box"></div>       <div class="box"></div>       <div class="box"></div>       <div class="box"></div>   </div>