I agree with Velasco that it could be presented better but this is a great resource anyways. I wonder what cross border trends exist, if any. My guesses for cross border trends:
>Socdem ethnic russians in the Russian border with Latvia and Estonia
>The centre-right extending from Austria into SüdTyrol
>The centre-right extending from western Germany into rural North Luxembourg and eastern Belgium
>Spain and Portugal having very similar vote distributions
>Perhaps the most comical, the Liberals extending from the Spanish Basque Country (PNV) into the French Basque Country (LREM)
To be honest, the only "real" ones are the Spain/Portugal one and the Süd Tyrol one maybe. The other ones are pretty much just a coincidence
