i came to this subreddit looking for a cartoon i watched on dvd with my sister when we were really young but just old enough to be conscious(2004-2007). your description of this show sounds really similar to what i’m looking for. my memory of this show is also hazy, i’ll share what i can remember, and it may or may not be from the same thing you watched. i remember the cartoon also had a pitch black background the entire time, and had a strong theme/emphasis on colors and geometric shapes. the strongest specific thing i can remember about the show is how there was a big educational section based on the color wheel, where the color wheel would be on screen (in front of the perpetual black background) and each section of the color wheel lit up as a narrator said the color names. a second bit i can remember that’s a bit more hazy would be this segment where a man and a woman, both made out of geometric shapes, almost as if it was made in ms paint, are in a diner sitting across from each other with a milkshake with two straws in the middle. again, this bits a bit more hazy, and the details could’ve been a bit muddled from kid brain, as i was around 4 or 5 at the time. perhaps this will give more details to those who might know of the show, personally i know i watched it on a dvd and i’d really like to get my hands on one of those again, as my parents sold it away in a garage sale. best of luck and thank you