It is also useful for users of text-only WWW tools like Lynx. All information conveyed with color must be available without color. Good primer on Color Blindness Link used with author's permission. Thirty percent of all males suffer from some form of color deficiency rendering colors as grays or spreading one color across several others. Choose text and background colors to provide maximum contrast.
Contrast is also very important for individuals who can see but have reduced vision.
Good design also refers to the ability of reader software to properly parse a page correctly left to right and up to down. Language identification Changes in natural language of document text and alt text equivalents must be clearly identified. This has important implications for international sites and also when using style sheets. Correctly tagged web pages, when seen by browsers with appropriate ISO character sets installed will properly render specific language character sets including accents and special characters or entities. Dynamic content Web pages shall update equivalents when the dynamic content changes.