Technical Requirements
Basic rules for the user interface:
- In the user interface of your web application, separate content (markup) from presentation (CSS) and behavior (JavaScript).
- JavaScript should as long as possible be written in an unobtrusive way with graceful degradation applied. This case can be overruled when the information that is presented is available to the user in an alternative way: if e.g. a street address is visualized with a JavaScript driven map, the address must also be available in regular text.
- Always use semantically correct markup, never use such things as tables for layout purposes, only to display tabular data.
- Use valid XHTML 1.0 Strict or HTML5 for your markup.
See also the sections Accessibility and Browser Support.