I have a simple HTML page with my name using the UTF-8 character encoding. This name is expressed in the Devanagari Script. This is how Firefox displays this on my Mac.
The same HTML page is displayed as expected in Safari on the same Mac.
The actual HTML page is as follows:
<html>
<title> Testing Devanagari on Mac/Firefox </title>
<h2>
My Name: केदार म्हसवडे
</h2>
</html>
