[Theodores]

Why support Internet Explorer?

Also the extra element attributes are not 'data-' attributes and will not validate as HTML5.

Webkit/Blink/Firefox on mobile/desktop is all there in the referred to article. Edge is soon to be Webkit so for me the target browser list is not as extensive as for some. IE is depreciated and was never HTML5.

Can we just have this smaller list of browsers, CSS only and HTML5 valid with no warnings?

Apart from that, great work!

[frosted-panel]

I should probably follow the spec, but I think having "data-" prepended to every custom attribute on the frosted-panel div will take up unnecessary space.

Why support IE you ask? Why not? Some clients force their devs to support legacy browsers such as Internet Explorer.