<!DOCTYPE html>
<html reftest-async-scroll
      reftest-displayport-x="0" reftest-displayport-y="0"
      reftest-displayport-w="800" reftest-displayport-h="2150"
      reftest-async-scroll-x="0" reftest-async-scroll-y="1050">
<meta name="viewport" content="width=device-width">
<style>
html, body {
    margin: 0;
    scrollbar-width: none;
}
.spacer {
    height: 100vh;
    background-color: green;
}
.sticky_bottom {
    position: sticky;
    bottom: 20px;
    height: 50px;
    background-color: blue;
    opacity: 50%;
}
.sticky_both {
    position: sticky;
    top: 20px;
    bottom: 20px;
    height: 50px;
    background-color: purple;
    opacity: 50%;
}
.sticky_top {
    position: sticky;
    top: 20px;
    height: 50px;
    background-color: red;
    opacity: 50%;
}
</style>
<div class="spacer"></div>
<div class="sticky_bottom"></div>
<div class="sticky_both"></div>
<div class="sticky_top"></div>
<div class="spacer"></div>