Hi,
the problem is the different HTML-code support between the Flashplayer and real browsers.
e.g. the Flashplayer with its limited HTML support needs the fontsizes defined with:
<font ... size="16px"> ... </font>
where on the other side real browsers in HTML5 needs to have a 'style':
<tag ... style="font-size:16px"> ... </tag>
Here a way to combine both to make it working in Flash and HTML5:
<font size="16px" style="font-size:16px"> ... </font>
The Flashplayer sees the <font> tag with the size setting and the HTML5 browser see an unknown tag (will act like a <span> element) but with a style and so applies the style to the enclosed content.
See also here about the unsupported <font> tag in HTML5:
http://www.w3schools.com/tags/tag_font.asp
Best regards,
Klaus