""Was there a blue equivalent for boys?""
No, there wasn't because David & Goliath started out making products for 14-24 year old girls/women.
They're starting to do stuff for Men, as well.
I've seen this range for years, my DD went from Emoish to Goth.
It's meant ironically and actually it's similar to what Amy often says to Penny, in the Big Bang Theory.