Package: fontconfig-config Version: 2.4.2-1.2 With the default font configuration, Arial and the other fonts that make up the MS Core Fonts aren't remapped/aliased to any sane alternative. Thus, if Arial is used by a website in a browser that uses the system default font configuration, it will fall back on a font that is less-than-sane (in the case of debian.org, you can see it fall back to *bitmap Helvetica*). It would be nice to use a font like DejaVu Sans if Arial is requested by the system (this is what is done on Ubuntu).
I tried to find where Debian and Ubuntu's font configuration diverges (to figure out how to make this fix) but was unsuccessful in doing so. Hopefully the fontconfig maintainer(s) may be able to locate this in order to fix the issue.