There are lots of reasons to use a CSS layout. By a CSS layout I don't mean you just set you font color with CSS and removed the underline from links. But I mean the very positioning of everything is done with CSS. The alternative option is tables, which is not a good way to layout a site. But I am not saying don't use tables. Tables have a purpose, namely to display tabular data, much like you would put in Excel. But they are not meant for the layout of your site, they were not designed to do so, and therefore they are an inferior method of doing it. The whole idea of CSS is to separate content from layout and style. Letting to change one, with out the other getting in the road.
One very important reason that anyone should consider learning CSS for is maintainability. If you have 500 websites, and you need to move something. How do you go about it? Well with tables you spend a few hours editing every single page to move the item. CSS you change ONE file and the job is done. Ok, you could just chose not to change anything, but if your doing the site for someone else, paid or not, you just might not have a choice. It might take longer to edited that one CSS file, the to edit 1 page, but it going to be a lot quick than editing 500 pages. If you don't believe me have a look at http://www.csszengarden.com/ which is a contest of how much you can change the look of the page by just editing the CSS file. You will notice that sometimes the menu is on one side sometime on another. Some even split the content up into several columns.
The next reason is page size. CSS page tend to be much smaller. The lack all the <tr><td> littered every where (which also makes them more readable). Smaller pages sizes if it means nothing else, does mean a slightly higher search ranking. This is because search engines like a high content to code ratio. It can also mean $$$. Smaller pages mean less disk space, and less bandwidth. If your getting hard pushed for either of these CSS could be your life line. Not only does it mean smaller pages, but the CSS file only gets downloaded once and is saved by the browser.
To be continued....
Edited by Michael, 17 January 2007 - 06:40 AM.