Considering the design of inclusive interfaces of static and dynamic Web pages, this work focuses on the group of users with cognitive/intellectual disabilities, while simultaneously accounting for the needs of users with mobility and sensory deficits. A number of specific universal design principles are derived from a variety of cognitive disabilities, such as problems with linguistics (text and language), learning and problem solving, orientation, focus and attention span, memory, and visual comprehension. The principles have been implemented and evaluated by means of personas testing with results showing that a much more universally accessible solution of a login mechanism to a Web service could be achieved as compared to today's solution.