It has a very high polish and seems to work well for the mock retro board I created. 3 likes might be a bit small of a default value IMO. Good job on the project, it looks better than whatever we use at work.
I am confused with the header nav links, particularly how the "Planning Poker" and "Retrospectives" items swap positions on click - but don't actually navigate to the page itself (just to a landing page?) When I click "Start Reflecting" on the "Retrospectives" page it directs to Planning Poker creation.
On the "Start Reflecting" nav item it appears only the "Start" text contains a click handler - clicking the "Reflecting" text doesn't do anything.
Cheers and good luck