Flex Jiugongge layout

design sketch

html

<div class="gridBox">
    <div class="cellLi">1</div>
    <div class="cellLi">2</div>
    <div class="cellLi">3</div>
    <div class="cellLi">4</div>
    <div class="cellLi">5</div>
    <div class="cellLi">6</div>
    <div class="cellLi">7</div>
    <div class="cellLi">8</div>
    <div class="cellLi">9</div>
</div>

 css

.gridBox{
    background-color: #f5f5f5;
    overflow: hidden;
    margin: 20px 0;
    display: flex;
    flex-wrap: wrap;
}

.cellLi{
    width: calc(100% / 3);
    padding: 60px 0;
    text-align: center;
    border: 1px solid #f5f5f5;
	box-sizing: border-box;
	background-color: #fff;
    overflow: hidden;
}