Hi Acrylian,
the strange thing is that it does not happen everytime.
I am pretty sure it must be the static_html plugin because:
1.
This does not happen when i am logged in to zenphoto as an admin - did it with firefox
As far as i understood the plugin does not cache the site when viewed with an admin login
2.
Have the site open in chrome where i am not logged in. There i can see the behaviour.
3.
Logged out in firefox: Font size increased like in chrome
4.
Disabled the plugin an everything looks fine.
So my guess it is something related to the theme/plugin combination.
With one of the standard themes this does not happen.
Will have a look with firebug when it occurs the next time.