Stylesheet
A stylesheet can be described as a format template. It is intended to separate information from presentation. Data such as texts, tables, graphics are interpreted and formatted according to predefined rules. The editing languages of the stylesheets are called stylesheet languages. Among the best known are CSS, XSL, DSSSL.
Cascading stylesheet
A cascading style sheet (CSS) is a language for a design template of structured documents. CSS is mainly used with HTML and XML. Whereby with HTML or XML the subdivision of the document concerning the contents and with CSS the concrete representation are specified as for example color, font characteristics, layout. With the help of the CSS rules concrete values for different representation attributes can be determined, whereby this determination takes place at a central place or even in a separate document. The instruction can be formulated thereby completely generally whereby it is asked, which place a characteristic is to take a certain value. The combination of property and value is represented with a curly bracket {}. With a semicolon (;) after the value, this combination is completed and is very important. With this stylesheet language it is possible to get different representations for different output media. For this reason, for example, hyperlinks can be executed separately when printing a document. CSS is also able to design elements in more detail, to position them freely or even to animate them.
Integration of CSS in HTML pages
A style sheet can be integrated directly in the source code, at the beginning of an HTML page or in an extra CSS file. If the integration takes place at the beginning of the HTML page, then CSS properties are specified and have an influence on the entire document. It is possible to outsource the stylesheets from a HTML. This outsourcing brings many advantages, such as an integration of the stylesheet in several or all HTML documents of a web project. Styles therefore only have to be defined once and can then be used for all documents. In the head of the HTML document there is a link which points to the external stylesheet.
Other stylesheet languages
Another stylesheet language is XSL (Extensible Stylesheet Language) and is used to extend XML documents. It is a transformation language for defining the layout of an XML document. Compared to CSS, the formatting possibilities of XSL are more oriented towards the requirements of print publications. The individual stylesheets can be assigned to different media, so that it is possible to use a layout for the printer and a layout for the computer. XSL is a forerunner of DSSSL (Document Style Semantics and Specific Language) a transformation language for SGML documents. This stylesheet language contains a real programming language and can additionally be used for calculations.
