Add fallbacks

[Awk34]

Things like hsla, external web-retrieved content (web fonts), and certain newer web components should have fall-backs for older browsers. We should use modernizr for feature detection, and maybe include polyfills for mandatory features.

[uber5001]

Things like hsla have pretty good support. We probably want to stick with more recent browsers for feature checking. As far as I'm concerned, if caniuse.com says the "current" version of a vendor's browser supports it, we're good to go.

[Awk34]

I guess you're right. I know Firefox and Chrome do silent updating now, not sure about other browsers.