Cascading Style Sheets (CSS) is a W3C standard mark-up language for defining the appearance of web pages. The use of CSS allows developers to fully separate the content of the page from its presentation, speeding up the development process and also making the pages load more quickly in the browser. Whereas 20th century websites typically used tables to construct web pages and position elements, CSS now provides a cleaner and more efficient way of controlling all aspects of web page layout.

Adobe Dreamweaver is a very widely used platform for developing web sites and web content and, although used by experienced developers, is also widely used by non-specialists for whom Dreamweaver's user-friendly visual interface takes the pain out of web site creation. The way in which Dreamweaver implements CSS is very important for the casual user, since it will influence the kind of sites they end up producing.

Previous versions of Dreamweaver assumed that most users would be using tables to control the layout of their web pages. Dreamweaver CS3 is the first version of the program which encourages users to create CSS-based web page layouts. When the users create a new web page, they are offered a series of CSS layouts, on which they can base the new page, consisting of single, double and three column designs.

Instead of using tables to control positioning of web page content, CSS page layout makes extensive using of the DIV element an HTML construct which can contain just about anything, including other DIVs. The preset pages created by Dreamweaver CS3 contain a series of DIV element with the CSS code that controls their positioning. The placeholder text within the DIVs includes useful tips on customising the preset pages for your own use.

CSS works most efficiently when you can place all of your CSS code in one external file and link that file to each of your HTML pages. Dreamweaver CS3 still does not make it easy for inexperienced users to create CSS-based pages in this way. If the user creates ten web pages based on Dreamweaver's preset CSS designs, each will have its own code embedded within the page itself. There is, however, a great feature for moving embedded code across to an external CSS file. You just select a series of CSS definitions, right-click and choose "Move CSS Rules" which is available in the "CSS Styles" section of the context menu.

Although this ability to move CSS around is really great, it's not something that beginners will necessarily think of doing. It points to the fact that Dreamweaver could still do with a few enhancements to its implementation of CSS.

Dreamweaver CS3 still has includes the automatic creation of CSS styles whenever the user applies font attributes to text. Simply removing the ability to select text and apply these basic attributes would prevent this from happening. From a beginner's point of view, it would be far more useful to just have a "Style" menu with an option to create a new style if no styles already exist.