CSS Introduction

File extension:	.css
MIME type:	text/html
Type code:	TEXT
Uniform Type Identifier:	public.html
Developed by:	World Wide Web Consortium (W3C)
Type of format:	How to Display HTML Elements
Extended to:	CSS2
Standard(s):	CSS1,CSS2,CSS2.1

Cascading Style Sheets (CSS) are a way to control the look and feel of your HTML documents into an organized and efficient manner.

With CSS you will be able to:

Add new look to your old HTML
Completely restyle a web site with only a few changes into your CSS code
Use the "style" you can create on any webpage you wish

A CSS file must have a .css file extension

A CSS file can be created using a simple text editor

CSS is a program that runs inside Web Browser

Scripts in CSS file are executed on the Client

What Is CSS?

CSS stands for Cascading Style Sheets
Styles define how to display HTML elements
Styles are normally stored in Style Sheets
Styles were added to HTML 4.0 to solve a problem
External Style Sheets can save you a lot of work
External Style Sheets are stored in CSS files
Multiple style definitions will cascade into one

Intended Audience

We suggest that you check to see you meet the following recommendations before you begin the CSS Tutorial :

You have used HTML before.
You have basic idea about HTML tags and vocabulary.
You want to be a better web designer!

If you do not, we recommend that you check out our HTML Tutorial before taking on CSS.

When you are ready, continue the tutorial to learn about the basic form of CSS and where you should place your CSS code.

Styles Solve a Common Problem

To define the content of a document,HTML tags were originally designed.By using tags like <h1>, <p>, <table>,they were supposed to say "This is a header", "This is a paragraph", "This is a table" and so on.Without using any formatting tags ,the layout of the document was supposed to be taken care of by the browser.

It became more and more difficult to create Web sites where the content of HTML documents was clearly separated from the document's presentation layout as the two major browsers - Netscape and Internet Explorer - continued to add new HTML tags and attributes (like the <font> tag and the color attribute) to the original HTML specification .

To solve this problem, the World Wide Web Consortium (W3C) - the non profit, standard setting consortium, responsible for standardizing HTML - created STYLES in addition to HTML 4.0.

Cascading Style Sheets is supported by all major browsers .

Style Sheets Can Save a Lot of Work

HOW HTML elements are to be displayed is defined by Styles sheets , just like the font tag and the color attribute in HTML 3.2. Styles are normally saved in external .css files. you can change the appearance and layout of all the pages in your Web using External style sheets , just by editing one single CSS document! CSS allows developers to control the style and layout of multiple Web pages all at once so that it is a breakthrough in Web design . It is possible to define a style for each HTML element and apply it to as many Web pages as you want.To make a global change,all elements in the Web are updated automatically by simply changing the style.

» Multiple Styles Will Cascade Into One

To be specified in many ways,Style Sheets allow style information. Inside a single HTML element which can be inside the <head>element of an HTML page, or in an external CSS file,Styles can be specified. Even inside a single HTML document,multiple external style sheets can be referenced.

Cascading Order

» What style will be used when there is more than one style specified for an HTML element?

By the following rules, all the styles will "cascade" into a new "virtual" style sheet , whereas fourth one has the highest priority:

Browser default
External style sheet
Internal style sheet (inside the <head> tag)
Inline style (inside an HTML element)

Inline style sheet will override a style declared inside the <head>that's why an inline style (inside an HTML element) has the highest priority in comparision to an external style sheet, or in a browser (a default value).

» What You Should Already Know?

You should have some basic understanding of the following before you start: