position: sticky
// css 部分
.container {
background-color: oldlace;
height: 200px;
width: 140px;
overflow: auto;
}
.container div {
height: 20px;
background-color: aqua;
border: 1px solid;
}
.container .header {
position: sticky;
top: 0;
background-color: rgb(187, 153, 153);
}
// html 部分
<div class="container">
<div class="header">Header</div>
<div>1</div>
<div>2</div>
<div>3</div>
</div>