Let's take a look at them:
The first and most important rule for the developer is separating the content and layout:
One of the most important requirements for practical accessibility is content that can be output in a linear format and that is formatted exclusively with CSS.
Only by abiding by this, can Assistive Technology prepare the content as it needs to while ignoring the visual presentation. The removal of the presentation into style sheets allows, for example, the visually-impaired users to define their own style sheets in ...