scroll-behavior

scroll-behavior: auto;

scroll-behavior: smooth;

<section id="default-example">
  <div class="container">
    <p class="nav">
      Scroll to:
      <a href="#pageA">A</a>
      <a href="#pageB">B</a>
      <a href="#pageC">C</a>
    </p>
    <scroll-container id="example-element">
      <scroll-page id="pageA">A</scroll-page>
      <scroll-page id="pageB">B</scroll-page>
      <scroll-page id="pageC">C</scroll-page>
    </scroll-container>
  </div>
</section>

/* stylelint-disable selector-type-no-unknown */
.container {
  flex-direction: column;
}

.nav a {
  color: #009e5f;
}

scroll-container {
  border: 1px solid black;
  display: block;
  height: 200px;
  overflow-y: scroll;
  width: 200px;
}

scroll-page {
  align-items: center;
  display: flex;
  font-size: 5em;
  height: 100%;
  justify-content: center;
}

/* Keyword values */
scroll-behavior: auto;
scroll-behavior: smooth;

/* Global values */
scroll-behavior: inherit;
scroll-behavior: initial;
scroll-behavior: unset;

<nav>
  <a href="#page-1">1</a>
  <a href="#page-2">2</a>
  <a href="#page-3">3</a>
</nav>
<scroll-container>
  <scroll-page id="page-1">1</scroll-page>
  <scroll-page id="page-2">2</scroll-page>
  <scroll-page id="page-3">3</scroll-page>
</scroll-container>

a {
  display: inline-block;
  width: 50px;
  text-decoration: none;
}
nav,
scroll-container {
  display: block;
  margin: 0 auto;
  text-align: center;
}
nav {
  width: 339px;
  padding: 5px;
  border: 1px solid black;
}
scroll-container {
  display: block;
  width: 350px;
  height: 200px;
  overflow-y: scroll;
  scroll-behavior: smooth;
}
scroll-page {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100%;
  font-size: 5em;
}