Incredible work @holger80! Most impressing how fast you managed to create this.
Just a sidenote:
This app isn't limited to referred accounts created by hiveonboard, since every dApp could use the Open Standard Referral System right now. One example would be https://quello.io which adapted this system from early on and are creating accounts following this system as well.
Just now looking into if Hive onboarding through linkedin would be viable, have to look up with the open standard referral system is...