I've recently been told that the opposite of yellow is indigo (ocean blue) so I had to see for myself by using "persistence of vision", a visual trick that allows you to see the exact opposite of a color (according to your eyeballs, not any color wheel you've learned from) after staring at at a color for a long moment. I put 9 colors on different pages and did this trick to see what color I'd get after switching to the white page afterwards. Then I filled in the page with the color I saw and moved onto the next color. I did this until I got the true opposite of each 9 colors and then made a few color wheels with them. Hope someone finds this interesting and learns something too. If you want to test it just pause on each color screen for 30-60 seconds and then let it play until the white screen that comes after, make sure to pause on it so you can take in the illusion.