HTML 5 is conceptually divided into two parts: (1) HTML 5 Core (the HTML markup seen on the page, semantic elements, video and audio features) and (2) HTML 5 Web Application – features like canvas, web sockets, server-sent events and so on. CSS 3 is the latest standard for CSS. It is completely backwards-compatible with earlier versions of CSS. It is divided into modules, as known as the old CSS specification (further divided into smaller parts) and there are new modules added as well. Some of which are: Selectors, Box Model, Backgrounds and Borders, Image Values and Replaced Content, Text Effects, 2D/3D Transformations, Animations, Multiple Column Layout, User Interface, etc.
Hire developers working on HTML 5 and CSS 3, as they would build applications and websites that the modern browsers will support!