@noonnope -- No actually, that doesn't answer my question because you resized it smaller, so I can't tell if those are 2px or 3px or the 4px they are supposed to be between the elements... much less you didn't test other font-faces/styles.
Make a second one and set it to bold, and don't resize the image smaller. try it at each increment of font-size 1px at a time from 10px to 16px -- see what happens to the border.
But then the only solution I can think of given all the other restrictions is either negative margin or letter-spacing, and again those aren't a correct answer to the question... so unless there's some magical -webkit property I'm unaware of...
That might explain the OSX test, since that's where I'm using VirtualBox... Doesn't explain the native copy of chrome I'm running on the host OR the VB copy I just installed trying to track it down. Since I have a 7 install for "7 on 7" with small fonts, it was easy enough to install Chrome there to see if maybe the host OS or my system metric was at fault. It ALSO appears to break in XP in a VM, but I went over to my netbook which is on same version of Win7 -- and it works there.
Which has me wondering if maybe it's a processor level difference or something weird like that. Rounding error or difference on the i7 870 compared to other processors?
Eh, wouldn't be the first time -- I've had allegedly identical machines with identical XP installs with the same versions of IE7 give me different appearances; Often seems I'm cursed like that... Either that or M$ is just toying with our minds by giving us different versions based on the registration key.
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Actually, they're NOT identical OS versions between the netbook and desktop. They're both ultimate x64, but the workstation is VLE while the netbook is "System Builders".
Uhg, do I want to try installing OSX under virtualBox on a netbook for testing?
-- edit edit --
on .nav fixes the solution to this challenge not working in Chrome/Win and Saffy/Mac here. Damned if I know why - I just started going down the list of proprietary properties and throwing them at it.