The change from pt to px is one of the "usual suspects." They are related as follows:
px = pt*dpi/72where dpi (dots-per-inch) is the resolution (pixel density) of the device (screen, printer, etc.) you are using. Yours appears to be 96 dpi (or you may have set your system to 96 dpi). Hence you getpx = 10*96/72 = 13 px (rounded).13 pixel look like 10pt on your screen. But on my screen (120 dpi) they don't. Solving for pt yields
pt = px*72/dpihence
pt = 13*72/120 = 8 pt (rounded).There is a plethora of opinions and anecdotal wisdom on the internet, but
I forgot the default settings in Firefox or Chrome, as they are usually too small and thus are the first things I change. So... if you set the font size to 1em, the text may look larger than you want in IE and, at least with the default settings, smaller in FF or Chrome.
- The problem with px is that it gets you a different (physical) size depending on your screen's dpi, and it doesn't respond to changing the text size to "larger" in IE6 and probably below (which is why I switched to Firefox).
- The problem with pt is that it doesn't respond to changing the text size in IE6 (but it gets you the same [physical] text size on any dpi).
- The w3c recommends using the "em" instead of either px or pt (see http://www.w3.org/WAI/GL/css2em.htm). The "em" is sort of a "relative" font size specification in that it refers to the default font size of the browser. 1em = 100% of the default font size. IE6 and IE7 appear to "hard-wire" this default to 12pt, while Firefox or Chrome users get to choose a default size (in pixels).
It's a bit of a mess with all the various browsers out there, which may explain the relative confidence in specifying things in pixels. Except that this gets some users a smaller physical font size, which is why I prefer pt or em in my CSS/html.
As to the actual typeface being used, this appears to be a glitch. I just displayed this thread in IE7 and FF3 side-by-side. IE shows your post in Tahoma, while FF in Verdana. Go figure... but don't lose any sleep over it.