<html>
<head>
<meta charset="utf-8">
<head>
<script>
function go() {
  a.show();
  document.execCommand("bold", false);
  b.style.setProperty("font", "0px/43%");
  document.execCommand("insertText", false, "a");
}
</script>
</head>
<body onload=go()>
<ul contenteditable="true">
<li id="b" style="font-weight: bolder">a</li>
<dialog id="a" tabindex="0">a</dialog>
</ul>
</body>
</html>
