Default CSS style has font family defined as follows:

<code>font-family: "sans serif";</code>

While "sans serif" is an actual name of font in some Linux installations, this doesn't work for e.g. Safari on Mac -- it falls back to the default serif font (Times New Roman).

The proper way to define a generic sans-serif font in CSS, according to CSS specs is this:

<code>font-family: sans-serif;</code>

Note the dash and absence of quotes (from specs: <i>Generic font family names are keywords and must NOT be quoted</i>).