A style sheet is made up of style rules that tell a browser how to present a document. There are various ways of linking these style rules to your HTML documents, but the simplest method for starting out is to use HTML's STYLE element. This element is placed in the document HEAD, and it contains the style rules for the page.
Note that while the STYLE element is a good method of experimenting with style sheets, it has disadvantages that should be considered before one uses this method in practice. The advantages and disadvantages of the various methods are discussed in the section on linking style sheets to HTML.
Each rule is made up of a selector--usually an HTML element such as BODY, P, or EM--and the style to be applied to the selector.
There are numerous properties that may be defined for an element. Each property takes a value, which together with the property describes how the selector should be presented.
Style rules are formed as follows:
selector { property: value }Multiple style declarations for a single selector may be separated by a semicolon:
selector { property1: value1; property2: value2 }
As an example, the following code segment defines the color and font-size properties for H1 and H2 elements:
<HEAD> <TITLE>CSS Example</TITLE> <STYLE TYPE="text/css">H1 { font-size: x-large; color: red } H2 { font-size: large; color: blue }</STYLE> </HEAD>
You can also write a style sheet pages and save it as a text document with a .css extension such as style.css
using the following code: H1 { font-size: x-large; color: red }
H2 { font-size: large; color: blue }Then link you web pages to it using the following code in the head section or each of your web pages in your site.
<link rel="Style Sheet" href="style.css">
Then when you want to change a tag in your web site just change the values in your style sheet and all your pages will be changed automatically.
The above style sheet tells the browser to show level-one headings in an extra-large, red font, and to show level-two headings in a large, blue font. The CSS1 Specification formally defines all properties and values available.
This tutorial is intended as a very basic introduction to Cascading Style Sheets and should provide enough information to allow you to experiment with a few of your own styles. For a more in-depth look at Cascading Style Sheets, read the following sections: