Cascading Style Sheet (or CSS in short) allows you to style each element in a web page so that you can customize it to contain a certain stucture, color, headers, fonts and backround etc. Using CSS can be an easy way to make your site stand out as well, if you know how to use it.
Designing with tables and/or CSS has been a debatable topic as some SEO will tell you that search engines doesn’t index sites with tables that well. This reason alone made quite a lot of people started to learn CSS. WordPress, for example, has lots of customizable themes where most authors merely have to define their own CSS styles and rules.
And honestly, when it comes to desgning web forms, it’s just so easy to draw a table and say “there you have it!”. Designing web forms with CSS takes a bit more work but doesn’t mean that it’s hard to do. The end result can be rewarding as you can have more control of it, you can style each part of it and you know it’s crawlable by search engine spiders.
In that regards, Sitepoint has published an excellent article about designing web forms using CSS which I enjoyed reading.
Have fun designing with CSS!