Looking at http://hg.mozilla.org/releases/l10n-mozilla-1.9.2/ca/file/4bd3e7220f7f/mobile/chrome/aboutHome.dtd#l1, "<span id='header-suffix'>Inici</span> del <span>&brandShortName;</span>" the 'del' is unstyled, I'd lean towards that being as shaded as Inici as opposed to be bright shiny white like "Firefox". I.e. Inici del *Firefox* rather than Inici *del Firefox*. Not sure, filing this bug for evaluation.
I'm not blocking beta on this, just to clarify.
Just cross-checked in the build and you are right, del (preposition+article), should be styled like 'Inici'. I will report here when I commit the changes.