Color contrast is an important but often overlooked aspect of web accessibility. Many more people are visually impaired or color blind than are legally blind. So by ignoring the color contrast of your page, you will be affecting a significant portion of your audience. During the design phase, you will want to check your web templates’ color contrast and adjust it accordingly. Although you can sense when a page has poor contrast, there are tools that can quantify the contrast between text and its background based on the style sheet and return a result in the form of a ratio. Websites that satisfy WCAG 2.0 must have a contrast ratio of 4.5:1 or higher.
See this site’s page on evaluating color contrast to learn how to determine if your web pages have sufficient contrast.