Sorry, your browser doesn't support CSS random() so it will default to a non-random value.
Please try this on Safari to see the function working.

This demo uses the experimental CSS function random(), which is currently supported only in Safari / WebKit browsers.

Because of how random() works, its value is calculated once when the page styles are first evaluated. That means the wheel does not generate a new random result on every spin — the same value is reused until the page is refreshed.
This is a limitation of the current implementation rather than the concept itself. Future browser updates and specification changes may allow random() to be recalculated dynamically (but I wouldn't count on it).