I opened a new document in Adobe Illustrator CS5, which defaults to CMYK as a color mode. I imported a raster image, used LiveTrace with 6 grayscale colors, expanded, and saved as SVG, which changed the color mode to RGB (which I believe makes no difference, since it's only grayscale colors at this point). In the text, I replaced black in the plain text of the SVG to one web color and gray with a tint of that web color, where the opacity is proportional to the amount of gray. In the example below, I used
MediumSlateBlue. I copied the design in the SVG file with
7B68EE into a CMYK document and the color became
Here are two images of the difference for this case. The SVG with
fill="#7B68EE" in the plain text:
The design pasted into a CMYK document:
A similar replacement happened from
FF9900 and from
66CC33. I wonder if it's a coincidence that the hexadecimal characters in Illustrator's colors are doubled, e.g.
I am using macOS Mojave 10.14.6 and Illustrator CS5 15.1.0 (yes, I really am, I was able to make them play nicely).
Why does Illustrator change
MediumSlateBlue (7B68EE) in an RGB document to
666699 in a CMYK document?