This movie has a cool aesthetic
As a kid of the 90s/00s I definitely remember that an updated spin on the 60s' mod look was popular, for at least a short while, and for me it's become kind of a nostalgic component of that period. When I see that look, I immediately think of how the turn of the current century made that callback to the 60s - probably because it came during my ever-impressionable preteen years.
Anyway, this movie reeeeally embraced it. Not many other teen movies of this time (and there are a lot to choose from within a five year span) had such a clear, cohesive aesthetic. It's everywhere - from the school, to Berke's house, the coffee shop, even the strip club. The look was in, but not to the point that it was everywhere. But that's part of what makes this movie memorable, I suppose. It knew what it wanted to look like and it achieved it pretty perfectly. It's one of the things I've always appreciated about it. It's like they put more effort into at least that aspect of the film, which most teen movie filmmakers wouldn't bother with.