The Web Content Accessibility Guidelines (WCAG) 2.0 contain recommendations from the World Wide Web Consortium (W3C) for making the web more accessible to users with disabilities, including color blindness and other vision deficiencies.
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There are three levels of conformance defined in WCAG 2.0, from lowest to highest: A, AA, and AAA. For text and images of text, AA is the minimum level that must be met.
AA compliance requires text and images of text to have a minimum color contrast ratio of 4.5:1. In other words, the lighter color in a pair must have four-and-a-half times as much
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