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In CSS3 First Look, staff author James Williamson provides an in-depth introduction to the newest CSS standard, detailing its modular format, history, and current level of browser support, while also demonstrating its capabilities and applications. The course includes tutorials on using new selectors, modifying typography and color, working with the box model, and understanding media queries. Exercise files accompany the course.
So before we get started I think it's important to answer a very basic question. What exactly is the CSS3? It sounds like a very easy question to answer. You can just say it's the latest CSS specification and the followup to the 2.1 specification. Except for the fact that it's really not. In fact, there is actually no such thing as the CSS3 specification at all, which could make this a pretty short title. And before we pack it all up and go home, let's take a brief look at the history of CSS, which will help us understand what CSS3 is really all about.
The CSS 1.0 specification was published in December of 1996. It was originally designed to help authors control the presentation of HTML. In fact, one of its earliest names was CHSS or Cascading HTML Style Sheets. Now thankfully, the H was removed, making it a easier to say and much more representative as a style sheet language that can be used for multiple markup languages, not just HTML. The 1.0 specification was quickly followed up by the CSS 2.0 specification, which was released as a recommendation in 1998.
Like any new standard CSS has had its share of growing pains. CSS 1 and 2 were released at a very volatile time in the development of web browsers. In the late 90s, browser manufacturers were not as interested in ensuring that their browsers were standards compliant. In many cases, browsers would introduce their own proprietary way of dealing with presentation or just offer uneven support for CSS. Now couple that with the fact that the CSS 2.0 specification continue to be updated, even though it was a published recommendation, and you had a real problem with CSS gaining traction.
In fact, to this day not a single browser fully implements the 2.0 specification. It was this environment that prompted the W3C to start work on revising the 2.0 specification. Now this revision, dubbed CSS 2.1, was issued as a candidate recommendation in 2004 and it's largely what people are talking about when they discuss CSS. Support for web standards continued to grow during the development of CSS 2.1 and browser manufactures began to get really serious about implementing the standard.
For the most part, modern browsers offer full implementation of the 2.1 standard. Now, you will notice I said for the most part. Because of uneven implementation, the W3C pulled the 2.1 specification back to Working Draft status in 2005 to even out the bugs and make the standard a bit stricter. Now it was returned to Candidate Recommendation in 2007 where it remains as of this recording. So let's try to summarize. The 2.0 specification was released and never fully implemented and the 2.1 revision was released, pulled back to Working Draft, and then released again as a Candidate Recommendation over the course of about six years.
Now saner minds might reason that the W3C should get one standard release and implement it before moving on to the next. But that line of thinking ignores the rapid evolution of the web. During the course of the development of CSS some very important changes have occurred in the way that websites are developed and consumed. The rise of online applications and mobile devices are just two of the changes that the original CSS specifications just weren't designed to address. With that in mind, the W3C is taking a very deliberate and in my opinion a very smart approach to developing the next generation of style sheet standards.
Although work on the CSS level 3 standard has been going on since at least 2001, the days of a large singular standards document that defines CSS is over. If the past history of CSS has taught us anything, it's that trying to get such an overwhelmingly large document through development and review and then publish it as a recommendation is extremely difficult. Because of this the W3C has decided to modularize the CSS standard. What is that mean? Well, essentially, it's been split up into various parts.
CSS selectors for example are defined in their own standard, while backgrounds and borders are defined in another. This approach allows the working group to have much more flexibility over the evolution of CSS. Individual standards can be developed based on different priority levels when needed and it's much easier to edit or add modules as the needs of web content changes. So, in fact, there is no CSS3 specification. There are simply individual specifications, some with a level 3 label, that are based on and meant to extend the 2.1 core specification.
All the future editions to CSS will either update existing modules or add new ones to the mix. Now while this is a smart way to make sure that evolution of CSS responds to the web community's needs, it can make it difficult to keep track of all of it. In our next movie we will do that by discussing the current state of CSS3 and by showing you how you can keep up with the development of the different modules.
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