<div class="box">
<div class="a"></div>
<div class="a"></div>
<div class="a"></div>
<div class="a"></div>
</div>
.a {
width: 20px;
height: 20px;
margin-right: 10px;
background: red;
position: relative;
}
.a::after {
content: 'xxx';
position: absolute;
top: -20px;
}
.box {
display: flex;
border: 1px solid black;
overflow-x: auto;
}