12th November 2007

Cascading style sheets (CSS) are a well established innovation from the World Wide Web Consortium (W3C), essentially a set of design rules for a website CSS allows design information to be centralised and every web page that links to the CSS file will inherit the design rules dictated by the file.

So why is this a good thing? Quite simply, the power to separate design from content.

Separating the design of a site from the content revolutionises the maintainability of websites.

Web sites with ease of maintenance designed in.

Web sites that do not use CSS have the design and presentation information written into each and every web page. On a 10 page web site this makes a design update a mild pain, on a 10,000 page web site it gets downright expensive.

When a web site uses CSS and the design is separated from the content a small change in one file will update any page that is linking to it, 10,000 web pages? No problem!

So we've got infinitely superior maintainability. Why else should I use CSS?

Web sites built for search engines.

Well, search engines love CSS web sites. Err...Well, not exactly. Search engines love web sites that have all of the design and presentation information removed; it makes their job of reading and interpreting a web page so much easier.

So we've got maintainability, ease of indexing by search engine. What else is there?

Leaner web sites that save money on bandwidth.

File size. Or more specifically smaller files. Switching to CSS can half the size of a typical HTML file, that means pages are quicker to load and your web server is using less bandwidth for the same page design.

And bandwidth = money.

Future proof with forwards compatibility.

If all that wasn't enough we've also got forwards compatibility.

We have heard a lot about backwards compatibility with many websites written to ensure that when someone visits the web site with a version 2 browser, they get the full design, often at the expense of the newer features of current web browsers for everyone else.

Developing to web standards.

What CSS in combination with web standards gives us is the ability to take advantage of newer features whilst at the same time providing a usable web site for older browsers.

And because these standards are used as a benchmark for new browsing device development such as mobile devices, so sites built in this way work exceptionally well for new and even future browsers.

So are you using CSS already?

Open up your web site and go view>source and look around for presentational information such as the <font> tag. And if you have them ask your web designer why.