Benefits of Cascading Style Sheets

Separate content from design - you can separate your HTML markup, text, graphics and scripting from the design.

Consistent site wide look and feel consistency - you can apply one style for 100s of web pages all at once.

Web site maintenance - apart from being able to makesite wide changes easily through one CSS file, the clean code it generates makes it easier to update.

Improve search engine rankings - search engines generally spider the code at the top of your web page first. For most sites that means the navigation bar will be spidered first (resides at top of page code). CSS enables you to position the code for your content at the top making your page search engine friendly. Properly marked up HTML pages can easily found and properly categorized by search engines.

Fast loading - CSS reduces the amount of tags used in the markup therefore producing clean code.

Accessibility - Content is more easily read by screen reading technologies.