Change font configuration to support Greek about gridgarden

[thomaspark]

Hi @lmintmate, first of all welcome and thanks for your contributions.

For languages whose glyphs aren't supported by the defined font (PT Sans in this case), the browser will fall back to another font that can support it, either a specific font named in the font-family property or a generic local font based on the sans-serif value. So there should be no problem rendering Greek characters.

If we do run into some styling issues, I can tweak after the fact. Let me know if you have any questions about doing a translation. Greek is one of the major languages we're missing for both Grid Garden and Flexbox Froggy so your translation would be very welcome.

[lmintmate]

Thanks for your reply. I'm aware there's a fallback font, often however it doesn't look very good compared to any non-Greek glyphs co-existing on the page. Your "wait and see" approach, as opposed to proactively elminating any such issues, is fine with me though, so I guess we'll see how it looks after I make the pull request and the translation goes live.
I already started translating, so I'll finish and do a pull request some time tomorrow at the latest (to make sure there aren't any typos).
P.S. I did find Flexbox Froggy soon after this one, and I might translate it in the future, but I'll have to play the tutorial of that one first, to get the feel of the layout and the terminology.