Why Use XHTML?
Web development is a war and we are soldiers, writing hacks and workarounds to make designs look right in buggy older browsers. What if tomorrow the war could be over? What if we could build sites that won’t fall apart in future browser releases? Isn’t that worth fighting for? Isn’t that worth developing for? XHTML encourages good practice. All your markup will be well-formed and all your tags will be closed. This makes page rendering easier for browsers and it makes bug-tracking easier for you. Best of all, using XHTML means that you must keep your presentation separate from your content. All you have to do is free your mind.
Why Use CSS?
Just imagine all the benefits that come with separating your presentation from your content. Your pages will be smaller, much smaller. Without the bloat that comes with nested tables, spacer images and font tags, your mark-up will be leaner and meaner. That will appeal to search engines. Life will be simpler for the people in charge of the design: the presentation of an entire site full of documents can be changed by altering just one file without ever touching the content. Life will also be simpler for the people in charge of the content: your mark-up will be human readable allowing the content be updated without changing the rules that govern the presentation. With Cascading Style Sheets, your content will be accessible to all browsing devices, past and present. That means everything from Lynx to web-enabled mobile devices and fridges. Remember, all I’m offering is the truth - nothing more.