What is CSS and CSS-P?

CSS = Cascading Style Sheets.
CSS-P = CSS Positioning (using CSS to position elements on a page).

CSS is a simple system for applying presentational styling to web pages and websites in a manner that is separate to the document's (X)HTML structure. The concept of CSS was first introduced by the World Wide Web's creator, Tim Berners-Lee, as far back as 1990, but it took another six years of discussion and development by different people around the world for it to finally become an officially recognised standard by the World Wide Web Consortium (W3C).

CSS is far more powerful than HTML styling, not only because entire layouts can be positioned with pixel-point accuracy, but because an entire website's styling instructions can be defined in one external stylesheet document. Thus by changing one line of code in the master stylesheet (e.g. a font colour), every instance of text affected by that style will be instantly modified thereafter, wherever it appears within the website.

Another advantage of CSS is that multiple stylesheets can be created, and then switched between by the site visitor if the mechanism to do so is provided by the site developer (click on the 'low graphics' link above for an example). Furthermore, sight-impaired users of particular browsers can create their own stylesheets to overrule a website's stylesheet such that text is displayed larger, or in a different colour, or set against a particular colour etc.