<?xml version="1.0" encoding="utf-8"?>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Drag and drop of overlapping links: zero height</title>
<style type="text/css">
span, strong
	{color:green;
	background-color:yellow;}
strong
	{color:red;}
div
	{width:4em;
	padding:1em;
	line-height:0;}
a
	{background-color:white;
	padding:1ex;}
</style>
<script type="application/ecmascript">
function start(event,feedback)
	{event.dataTransfer.effectAllowed = 'copy';
	event.dataTransfer.addElement(document.querySelector(feedback));}
</script>
</head>
<body>
<div>
	<a href="data:text/plain,1" ondragstart="start(event,'strong')">    </a>
	<a href="data:text/plain,2" ondragstart="start(event,'span')">Link</a>
</div>
<p>Try to drag link above. You should see word <span>PASS</span> not <strong>FAIL</strong> in feedback overlay all the time.</p>
</body>
</html>