Cascading Style Sheets (CSS) is a style sheet language that became the standard for formatting content inside an HTML document. Even though it’s mostly used for visual styles for web pages and user interfaces written in HTML / XHTML, it can also be applied to plain XML, SVG and XUL. The language has been designed to separate the content of the document from the document presentation (layout, colors, fonts etc.).


  • CSS allows the user to specify the details of an element only once, rather than every time the element is written in the code. This decreases the time and the updates required to create the web page
  • The pages are loaded faster, because less code is required for the CSS elements
  • Compared to HTML, CSS  contains a wider array of styles and attributes
  • CSS helps the web page to be indexed and ranked higher by search engines, thanks to the fact that it provides more content than code
  • CSS allows the user to create different stylesheets for the same web page. This can be very useful when designing a web page for mobile devices


  • CSS is an open text-based system, this means that it might enable anyone who has read and write privileges to change the formatting of the website just by changing the CSS files
  • CSS has been developed independently of HTML, therefore it’s required to know both languages in order to develop websites
  • Many properties have not reached a mature syntax yet

New components in CSS3

  • Upgraded Colors
  • Namespaces
  • Upgraded Selectors
  • Media Queries
  • Style Attributes
  • Multi-Column Layout
  • Backgrounds & Borders

Development tools

  • Wufoo
  • CSSTidy
  • Clean CSS
  • Browser inspectors
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