CSS is a way to add style to a document quickly and easily. It's the reccomended way to do this for several reasons:

1. CSS is predictable
2. CSS is fast: say you want to change the way your entire web page looks. Instead of mucking through several hundred documents, you just change a single document and everything looks different.
3. CSS is portable: it allows things to look good on many different types of media, including: screen readers, braille displays, hendheld devices, printers, projectors, monitors, tvs, and teletype devices.

The basic structure of CSS is esentially a list of styles. There are complicated rules about cascading, but those won't be looked into much during this tutorial. A typical stylesheet looks like this (only longer):

body {
margin: 0px;
padding: 5px;
background-color: #9091A8; }

#header {
height: 100px;
margin-bottom: 5px;
background-color: #D1EDC4;
border: 2px solid #000; }

.blocktext {
border: 2px solid black;
padding: 3px;
margin: 0px;
margin-bottom: 5px;
background-color: #fff; }

.minicontaincenter p a { text-decoration: none; }


There are a few ways of defining styles; these are known as "selectors." the selectors in the example above are seen before the opening bracket ( { ). A few types of selectors are:

• Universal selector: ( * ) The universal selector will define the style for any element. ( * { color: black; } will make all text black. )
• Type Selector: ( div ) The type selector is just a tag name. it defines a style for that tag.
• Class selector: ( .class ) The dot before a class name indicates a style for a specific class defined in the XHTML document.
• ID selector: ( #id ) The hash mark before an ID name indicates a style fpr a specific ID

In general, classes are used for elements that may occur more than once in a document, and IDs are used for elements that only occur once in a document. That's why we used an ID in the three sections of XHTML document made in lesson 1. We could have used classes for those sections without a problem, but using IDs makes it easier to maintain the stylesheet. In places you use classes, however, you can not use IDs. Using IDs in place of classes can lead to problems in some cases. Most often these problems only show up in validators. This lesson will not be looking at the basics of CSS itself, but rather will walk you through the basics of making a CSS layout for a web site. Lesson 3 will look closer at the basics of CSS styling.