Hexagons are supposed to have a gradual increasing opacity depending on the number of nodes located there. [The maximum is supposed to be `0.3`](https://github.com/nimiq/wallet/blob/f1a764c8e8692ac07aa48b034b71e5b8e2b6c58c/src/lib/NetworkMap.ts#L294-L295). 