A free micro-lesson here:

Look at my graphic I posted in #18. The shading on the side of the box is the red of the stripe plus a light blue...light blue is often used in cartooning to force the suggestion of coldness or darkness in an outdoors scene.

Our eyes might tell us that the left stripe side of my cartoon is dimmed-down red, but actually, it's close to olive green. Which is what happens in the real world, created out of subtractive (reflective) colour, when red and blue are mixed. On the monitor, additive colour creates an opposite effect, and not really natural because it's not physical colour. On our computers, red+blue=some shade of violet.

Click image for larger version.  Name: green-not-purple.jpg  Views: 364  Size: 28.3 KB  ID: 111046

This wasn't a thing that Xara could tell me. I was told by one of my art teachers back in 1972. :)

My Best,

Gary