Those aren't Mac fonts. A similar Mac font is Helvetica.
So you'd declare your font as:
font-family: Arial, Verdana, Tahoma, Helvetica, sans-serif;
If you don't have access to all three platforms, then generic fonts are your best bet. Though given all the *nix variants, one *nix platform may not have the same available fonts as another. From my own experience, they've been consistent. Generic fonts are always available though (provided the browser supports them, many do).
sans-serif (Arial, Helvetica)
serif (Times, Times New Roman)
monospace (Courier, Courier New)
In my own research I've found serif, sans-serif and monospace to be the most consistent.
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