Websocket fallback is long polling but it's not efficient. Especially if it's polling every 1 or 3 seconds, but it does work in a pinch. Web sockets can be a pain to get working correctly, depending on your stack. Try to be polite about the length of polling, especially if users are on their mobile phone. Maybe detect if it's mobile and/or not wifi then lengthen the time for ajax polling.
calc is pretty sweet! CSS is slowing turning into a programming language. Check out the CSS grid, it's very mathy.
Websocket fallback is long polling but it's not efficient. Especially if it's polling every 1 or 3 seconds, but it does work in a pinch. Web sockets can be a pain to get working correctly, depending on your stack. Try to be polite about the length of polling, especially if users are on their mobile phone. Maybe detect if it's mobile and/or not wifi then lengthen the time for ajax polling.