Updated fontSize regex to also accept the 'px' suffix

I noticed that the html parser wasn't picking up our font-size values.  We are using 'px' for the size and not 'pt'.  For example:

```html
<div style="font-family: 'Helvetica';font-size: 16px;">
    Some content
</div>
```

This PR maintains the 'pt' suffix and adds the 'px' suffix to valid font sizes parsed in.