SOURCE

<div class="container">
    <div class="inner">
        <div class="very-high"></div>
    </div>
    <div class="very-high"></div>
</div>

.container {
    width: 200px;
    height: 500px;
    border: 1px solid red;
    overflow: auto;
}

.inner {
    width: 100%;
    height: 300px;
    border: 1px solid blue;
    overflow: auto;
    /* overscroll-behavior: contain; */
}

.very-high {
    height: 1000px;
}