<!DOCTYPE html>
<meta name="viewport" content="width=device-width,initial-scale=1">
<style>
pre, #log {
  position: absolute;
  top: 0;
  left: 200px;
}
</style>
<iframe id="target-iframe" src="resources/observer-in-iframe-subframe.html" width="150px" height="150px"></iframe>
