<!DOCTYPE html> <!-- webkit-test-runner [ LayoutFormattingContextEnabled=true InlineFormattingContextIntegrationEnabled=false ] -->
<style>
.container {
  position: relative;
  height: 200px;
}

.child {
  width: 100px; 
  height: 50%;
  position: absolute; 
  top: 0px;
  left: 0px;
  background-color: green;
}
</style>
<div class=container><div class=child><div></div></div></div>