<div class="box">
<div class="column">
<span class="item">11</span>
<span class="item">12</span>
</div>
<div class="column">
<span class="item">21</span>
<span class="item">22</span>
</div>
</div>
.box {
display: flex;
flex-wrap: wrap;
align-content: space-between;
}
.column {
flex-basis: 100%;
display: flex;
justify-content: space-between;
}