CSS div顺序调整 (order属性的使用)

<div class="wrapper">
    <div class="yellow">
    </div>
    <div class="red">
    </div>
</div>

.wrapper {
  display: flex;
  flex-flow: row wrap;
}

.yellow {
    background: yellow;
    width: 20%;
    height: 300px;
}

.red {
    background: red;
    width: 20%;
    height: 300px;
}

@media screen and (max-width:600px) {
    .yellow {
        order: 2;
        width: 100%;
    }

    .red {
        order: 1;
        width: 100%;
    }
}