Sticky sections

Try to scroll the main content to see each section sticks to the top of page.
<div class="container">
<section class="container__section">
...
</section>
<!-- Repeat other sections -->
...
</div>
.container {
height: 100%;
overflow: scroll;
}
.container__section {
/* Take full size */
height: 100%;
width: 100%;
/* Stick to the top */
position: sticky;
top: 0;
}

See also

Sticky header

Sticky table column

Sticky table headers