<!DOCTYPE html>
<html>
<head>

<style id="firstLetterSheet">
  .fl:first-letter { }
</style>

<style id="emptySheet">
</style>

<script>

function boom()
{
  document.getElementById("firstLetterSheet").textContent = "";
  document.getElementById("emptySheet").textContent = ".aft:after { content: counter(chicken); }";
}

</script>

</head>

<body onload="boom()">

<div class="fl">Foo <span class="aft">Bar</span></div>

<p class="aft">Baz</p>

</body>
</html>