improve selected card visibility

[jaythomas]

trafficstars

Resolves #3.

Add extra border around the selected card to improve visibility. I couldn't get the backend and frontend to talk via websocket in order to test this, but I believe this change should do the trick.

[jackadamson]

Thank you for putting in a PR!
I just tried this change out locally, but found that the border radius didn't apply to the outline

Would you be able to change it so that the corners of the box are still rounded?

PS. An easy way to check out the UI without getting the backend running is by using Local Multiplayer (http://localhost:3000/#/l/) where you control both players.

[jackadamson]

Oh, and one thing that I noticed while initially trying out designs was that changing the border width when selected causes the div to grow, changing the layout of the cards. Make sure that selecting a card doesn't move it (or the other card)

[jaythomas]

@jackadamson I considered this and that's why I added an outline instead of increasing the border. Same visual effect without mutating spacing.