<div class="scroll-behavior-auto">
  <h3>scroll-behavior:auto;</h3>
<nav id="first">
  <a href="#one">1</a>
  <a href="#two">2</a>
  <a href="#three">3</a>
</nav>

<div class="scrolling-auto">
  <div id="one">One</div>
  <div id="two">Two</div>
  <div id="three">Three</div>
</div>
</div>

<div class="scroll-behavior-smooth">
  <h3>scroll-behavior:smooth;</h3>
<nav id="second">
  <a href="#four">1</a>
  <a href="#five">2</a>
  <a href="#six">3</a>
</nav>

<div class="scrolling-smooth">
  <div id="four">One</div>
  <div id="five">Two</div>
  <div id="six">Three</div>
</div>
</div>

body {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100vh;
}

.scroll-behavior-auto {
  margin-right: 25px;
}

h3 {
  text-align: center;
}
#first, #second {
  background-color: #2a9d8f;
  display: block;
  padding: 15px 0;
  text-align: center;
  width: 200px;
}

#first a {
  color: #fff;
  margin: 0 1em;
  text-decoration: none;
}

#second a {
  color: #fff;
  margin: 0 1em;
  text-decoration: none;
}

.scrolling-auto {
  background-color: #e9c46a;
  display: block;
  height: 200px;
  overflow-y: scroll;
  text-align: center;
  width: 200px;
}

.scrolling-smooth {
  background-color: #e9c46a;
  display: block;
  height: 200px;
  overflow-y: scroll;
  text-align: center;
  width: 200px;
  scroll-behavior: smooth;
}

#one, #two, #three, #four, #five, #six {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100%;
}