Using W3C standards:

Grammar XHTML 1.0 Transitional

Grammar for style sheets CSS 2.1

Web Content Accessibility Guidelines (WCAG level AA)

Presentation of the elements on the screen and of the contents in the code in a logical order.

Simplified navigation system consisting of a main menu.

Grammar XHTMLStrict y CSS 2.1

Accessibility Guidelines for Web Content ( WCAG AA level)