As there are different colors that people may be sensitive to, it is not enough to simply rule out the use of red and green in close proximity. When constructing your HTML page, it is helpful to view it on a black and white monitor to ensure high contrast and readability. Changing the background to a lighter color and returning the links to the default blue increase the accessibility of this page. There is now higher contrast between the two colors, making the text more readable. The use of color is problematic even for sighted Web visitors, as different monitors have different limits on the number of colors they can display.
Colorblind people have difficulty distinguishing colors.
Since the presentation of color depends heavily upon particular browsers and monitors, one solution is to view your Web design on multiple systems to gauge the accessibility of your color use. An even better test for colorblindness acceptability is to view the page with the color option turned off. If the text is difficult to read in shades of gray that is a good indication that the page is probably inaccessible to colorblind visitors. Suggests some questions to consider when designing a site that is accessible to color blind users.