请告诉我如何以 250 像素和 991 像素的分辨率在 2 列中正确布置 flex 元素。以下是它在移动设备上的外观:

我失败的代码:
.item {
background: red;
width: 300px;
height: 300px;
margin-bottom: 20px;
margin-right: 10px;
}
.items {
display: flex;
flex-wrap: wrap;
}
@media (min-width: 250px) and (max-width: 991px) {
.items {
flex-direction: column;
}
}
<div class="items">
<div class="item">
</div>
<div class="item">
</div>
<div class="item">
</div>
<div class="item">
</div>
<div class="item">
</div>
<div class="item">
</div>
</div>
如果我理解正确,这里是解决方案: https ://jsfiddle.net/ctka8z1y/
HTML:
css