Cascading Style Sheets (CSS) are a new feature in web site design added to HTML that gives both web site developers and users more control over how pages are displayed. With CSS, designers of the web site design and users can create style sheets that define how different elements, such as headers and links, appear. These style sheets can be added to any web site design on the web. The term cascading derives from the fact that multiple style sheets can be applied to the same Web page through web site design. Cascading Style Sheets (CSS) was developed for use in web site design from the World Wide Web Consortium, known as W3C. In web site design, Cascading Style Sheets (CSS) are important because it is a computer language that is used to write formatting instructions.
Web site design Cascading Style Sheets are used for the layout as in the position, alignment, width, and height, also for style such as the typeface, font-weight, color, and border. The CSS language was created to meet the aesthetic demands placed on web site design of HTML, the computer language used to author web pages. The Cascading Style Sheets language specifications set out how rules can be written and should be implemented by web browser developers in the web site design. Cascading Style Sheets rules are added to a webpage either by writing the code directly into the web site design
of the webpage HTML, or by linking to a separate file.A separate file containing only Cascading Style Sheets rules is commonly referred to as a ‘stylesheet', and has the extension .css. Cascading Style Sheets rules can be provided in a file that is separate to the web site design HTML. If all pages link to this centralized Cascading Style Sheets file, then the look of a web site design can more easily be updated.
For example, the color or size of all level-one headings can be changed by updating a single Cascading Style Sheets rule. Once a stylesheet has been downloaded, it is stored on the user's computer. For each subsequent webpage viewed, only the HTML needs to be downloaded. Once a webpage has been downloaded, a browser processes the underlying code in the web page design to determine how content should be displayed.
This process is referred to as rendering. The time a webpage takes to render is affected by the complexity of the code in the web page design that the browser receives. Using Cascading Style Sheets to control the layout of a page typically simplifies the code structure making it easier and faster for the browser to render. Additional features can be added to the web page design that provides hooks for technologies such as screen readers.
A screen reader is a program that reads aloud the interface to computer programs and computer-based content, including web pages. Cascading Style Sheets based techniques can be used to provide such hooks without impacting on the experience of mainstream users. For example additional headings can be added to content that will only be seen by a screen reader. These headings can be used to provide additional content information that would otherwise be communicated by the visual design.