Right... (deep breath)
Code:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<meta http-equiv="Content-Type" content= "text/html; charset=utf8" />
<style type="text/css">
span.rootkernel { border-style:solid none none none; border-width:1px; }
sup,sub { font-size:0.6em; }
sub.align {margin:auto 0.5em auto -0.5em;}
td.enumerator {border-style:none none solid none;border-width:1px;text-align:center;}
tr.denominator {height:1.8em;}
td.denominator {text-align:center;vertical-align:top;}
</style>
</head>
<body>
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim
veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea
commodo consequat.
<table style="vertical-align:text-top;font-size:0.5em;display:inline-table">
<tr>
<!-- integral symbol -->
<td rowspan="2">
<span style="margin-right:-0.1em;font-size:2.5em;">∫</span>
</td>
<!-- integral limits -->
<td><sup>x</sup></td>
<!-- fraction -->
<td class="enumerator">
sin<sup>-1</sup> θ
</td>
<!-- integral symbol -->
<td rowspan="2" style="padding-bottom:0.4em;font-size:1.3em;">
d<i>x</i>
</td>
</tr>
<!-- fraction -->
<tr class="denominator">
<td><sub class="align">0</sub></td>
<td class="denominator">
<!-- square root -->
√<span class="rootkernel">a<sup>2</sup> + b<sup>2</sup><sub class="align">n</sub><i>x</i></span>
</td>
</tr>
</table>
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu
fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in
culpa qui officia deserunt mollit anim id est laborum.</p>
</body>
</html>
Not exactly readable, but not as ugly as I feared it could get. Of course in real life you wouldn't put a formula like this inline, but this is a proof of concept. I was pleasantly surprised that reducing font size of <sup>/<sub> seems to make them more well-behaved. This is what it look like in Chrome:
