<!DOCTYPE html>
<style>
div {
  height: 100px;
  width: 100px;
}
.container {
  display: flex;
}
.paintcontain {
  contain: paint;
}
</style>
<!-- PASS if the green box is visible -->
<div class=container>
  <div class=paintcontain><div style="background-color: green;"></div></div>
  <div><div></div></div>
</div>