<!DOCTYPE html>
<meta name="viewport" content="initial-scale=10,width=device-width">
<style>
html, body {
  margin: 0;
  width: 100%;
  height: 100%;
  scrollbar-width: none;
}
#container {
  position: relative;
}
#inner {
  position: absolute;
  top: 0;
  left: 0;
  width: 10px;
  height: 10px;
  background: green;
}
</style>
<div id="container">
  <div id="inner"></div>
</div>