This is just a quick answer:

The ideology of National Socialism has been ridiculed and parodied (rightfully so) over the years on the the somewhat glaring irony that Aryans are (supposed to be ) blonde haired, blue eyed, yet most high ranking Nazi officials weren't.

But this is not the only way National Socialist pseudo-science understood Aryans as a racial category. Yes, the "Nordic races" (Northern Europeans) tended and tend to be blond haired and blue/green eyed and because of their association as also being Aryan, were viewed as the poster-children of a more isolated version of the "Superior Race". This absurd category of Aryan though had first to do with your ancestry and then second your actual physical apperance. If you could prove your German ancenstry went back several generations (with no intermarrying with Slavs, Jews, Africans, etc.) then this was just about all you needed. This isn't to say physical appearance wasn't noted or somewhat important (Reinhardt Heydrich was said to perhaps have had Jewish ancestry because of his nose by other Nazi officials, though this was likely some sort way to undermine him). Hope this helps somewhat. If you need any sources I can throw some your way, though I must admit National Socialist Racial Pseudo-science is not my speciality!