Cascading Style Sheets - Overview
HTML's original purpose was the efficient delivery of text documents
over limited bandwidth channels. To accomplish this efficiency, much of
the document formatting was left to the viewer's browser. In addition,
at that time commercial Internet traffic was forbidden. Little need
was seen for control of this formatting by the author. The Web
has evolved dramatically since then. A need for increased control
of formatting has emerged. This need has resulted in the appearance of
Cascading Style Sheet technology. In addition, this technology when
combined with JavaScript, can add dynamics to a Web page. More on this
in Module #8
What is a style sheet? A style sheet is a set of style rules,
written as a block of code, that tell a browser how to present a
document. Each rule includes:
- a selector - often a HTML tag such as <body> or <p>
- a property - such as font-family or margin-right
- a value - such as Comic Sans MS or 20%
The format for each rule is:
selector {property1:value1; property2:value2; ... }
For example, body {font-family:"Comic Sans MS"; margin-right:20%;}
is a rule.
In this module we will discuss the design and use of style sheets.
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