Tutorial

Links

Syntax

http://www.w3schools.com/css/css_syntax.asp

The CSS syntax is made up of three parts: a selector, a property and a value:

selector {property: value}

e.g.

body {color: black}

If the value is multiple words, put quotes around the value:

p {font-family: "sans serif"}

Note: If you wish to specify more than one property, you must separate each property with a semi-colon. The example below shows how to define a center aligned paragraph, with a red text color:

p {text-align:center;color:red}

To make the style definitions more readable, you can describe one property on each line, like this:

p
{
    text-align: center;
    color: black;
    font-family: arial
}

Grouping

You can group selectors. Separate each selector with a comma. In the example below we have grouped all the header elements. All header elements will be green:

h1,h2,h3,h4,h5,h6
{
    color: green
}

Selectors

Class Selector

With the class selector you can define different styles for the same type of HTML element. Say that you would like to have two types of paragraphs in your document: one right-aligned paragraph, and one center-aligned paragraph. Here is how you can do it with styles:

p.right {text-align: right}
p.center {text-align: center}

You have to use the class attribute in your HTML document:

<p class="right">
This paragraph will be right-aligned.
</p>

<p class="center">
This paragraph will be center-aligned.
</p>

You can also omit the tag name in the selector to define a style that will be used by all HTML elements that have a certain class. In the example below, all HTML elements with class="center" will be centre-aligned:

.center {text-align: center}

In the code below both the h1 element and the p element have class="center". This means that both elements will follow the rules in the ".center" selector:

<h1 class="center">
  This heading will be center-aligned
</h1>

<p class="center">
  This paragraph will also be center-aligned.
</p>

Note: Do NOT start a class name with a number! It will not work in Mozilla/Firefox.

ID Selector

A CSS ID selector contains a “#” immediately followed by the ID value:

The following ID selector matches the H1 element whose ID attribute has the value chapter1:

H1#chapter1 { text-align: center }

Comments

You can insert comments into CSS to explain your code, which can help you when you edit the source code at a later date. A comment will be ignored by the browser. A CSS comment begins with /*, and ends with */, like this:

/* This is a comment */

Embedded Style Sheet

<style type="text/css">
    .highlighted {
        background-color: yellow;
    }
</style>

External Style Sheet (Linking)

An external style sheet is ideal when the style is applied to many pages. With an external style sheet, you can change the look of an entire Web site by changing one file. Each page must link to the style sheet using the link tag. The link tag goes inside the head section:

<head>
  <link rel="stylesheet" type="text/css" href="mystyle.css" />
</head>

The browser will read the style definitions from the file mystyle.css, and format the document according to it.

An external style sheet can be written in any text editor. The file should not contain any html tags. Your style sheet should be saved with a .css extension. An example of a style sheet file is shown below:

hr {color: sienna}
p {margin-left: 20px}
body {background-image: url("images/back40.gif")}

Note: Do NOT leave spaces between the property value and the units! If you use margin-left: 20 px instead of margin-left: 20px it will only work properly in IE6 but it will not work in Mozilla/Firefox or Netscape.

Examples

Sample html and css files:

..\..\misc\howto\css\simple.css
..\..\misc\howto\css\simple.html