Mix navigation graphics done in browser-safe colors with full-color JPEG graphics
Just ignore it. Today all monitors can be set for thousands or millions of colors.
Dither the images you use as a web designer.
Yes, most of them see only in black and white
No. Most colorblind people can't see certain colors.
No. Colorblindness means you just can't see blues.
Don't use too many colors
Make sure color isn't the only way you share important information
Stick to really basic colors when designing a website