One of the greatest benefits of CSS and structural HTML, as we discussed back in the introduction to this guide, is the fact that it enables the creation of much more lightweight web pages than would otherwise be the case with appearance based HTML. If you are designing content that will largely be viewed using web browsers on PCs, however, this is much less of an issue than it used to be. There's an irony here. In the early days of the web, when transfer rates were slow, we only had high-bandwidth techniques (appearance-based markup, layouts created using tables, heavy use of images) available to us if we wanted to create captivating sites. Nowadays, when we can expect much higher transfer rates, we can use the much more bandwidth-friendly CSS+HTML4. But, as we have discussed previously, the web is not simply about browsers on PCs. For a long time now, the mobile web has been picking up momentum. But for the bust it would most likely be much more prevalent today. CSS is perfectly suited to designing appearance for content that will be viewed on devices which will have an extreme form of the limitations we worked under in the early days: low transfer rates and small low resolution, low color screens.
Not all aspects of the full CSS specification lend themselves to use on mobile platforms, so the W3C has developed the CSS Mobile Profile 1.0, which became a candidate recommendation (the last step before becoming a full recommendation) in July 2002. The mobile profile is a cut down version of the full CSS 2.1 specification, appropriate to mobile, or wireless devices. In fact, it is very similar to the old CSS 1. Regular CSS rules are obviously included in the mobile profile and the standard syntax is the same as for CSS 2.1. @import and @media rules are also an important part of this specification. This will allow developers to create different style sheets which will be used according to what type of device content is viewed on.
The following selectors are in the CSS 1.0 Mobile Profile
- type selectors
- descendant selectors
- child selectors
- link pseudo class selectors - only the
- dynamic pseudo class selectors - only the
- class selectors
- ID selectors
The following properties are in the CSS 1.0 Mobile Profile
- background (shortcut)
- the border properties
- the margin properties
- the padding properties