If installed on your system, this text should be displayed in Futura Condensed, a nice sans-serif. If you are looking at this page in Firefox or Opera on OS X, it appears in that face. Safari and the latest nightly build of WebKit (13244) use the standard Futura. Setting
font-stretch: condensed; has no effect.
Filed as WebKit bug #7709.
It appears that Safari does not support the text-decoration property within a span that is set to display: none until hovered (on which it is set to display: block, a la Eric Meyer’s css/edge).
I’ll post the files which revealed this issue in a day or two.
I also have seen some problems with the word-spacing property, which is supported, according to the MacEdition CSS2 support table.