Caniuse feature improvements

[marcoscaceres]

The caniuse feature could use a couple of improvements, which may help with both layout and accessibility:

• instead of being divs, we should probably use another <dl>
• we should redo the layout using CSS grid instead.
• The mobile view still needs improvement. In particular, the "more info" link should be on it's on row.

[sidvishnoi]

Also: https://w3c.github.io/web-share/ when images fail to load