what is css?

What You Should Already Know

Before you continue you should have a basic understanding of the following:

• HTML / XHTML

If you want to study these subjects first, find the tutorials on our Home page.

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What is CSS?

• CSS stands for Cascading Style Sheets
• Styles define how to display HTML elements
• Styles were added to HTML 4.0 to solve a problem
• External Style Sheets can save a lot of work
• External Style Sheets are stored in CSS files

  CSS Demo

  An HTML document can be displayed with different styles: See how it works
  

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  Styles Solved a Big Problem

  HTML was never intended to contain tags for formatting a document.
  HTML was intended to define the content of a document, like:
  <h1>This is a heading</h1>
  <p>This is a paragraph.</p>
  When tags like <font>, and color attributes were added to the HTML 3.2 specification, it started a nightmare for web developers. Development of large web sites, where fonts and color information were added to every single page, became a long and expensive process.
  To solve this problem, the World Wide Web Consortium (W3C) created CSS.
  In HTML 4.0, all formatting could be removed from the HTML document, and stored in a separate CSS file.
  All browsers support CSS today.
  

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  CSS Saves a Lot of Work!

  CSS defines HOW HTML elements are to be displayed.
  Styles are normally saved in external .css files. External style sheets enable you to change the appearance and layout of all the pages in a Web site, just by editing one single file!
  

  Examples

• Look at Example 1
• Look at Example 2

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CSS Syntax

A CSS rule has two main parts: a selector, and one or more declarations:

The selector is normally the HTML element you want to style.
Each declaration consists of a property and a value.
The property is the style attribute you want to change. Each property has a value.

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CSS Example

A CSS declaration always ends with a semicolon, and declaration groups are surrounded by curly brackets:

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

To make the CSS more readable, you can put one declaration on each line, like this:

Example

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

Try it yourself »

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CSS Comments

Comments are used to explain your code, and may help you when you edit the source code at a later date. Comments are ignored by browsers.
A CSS comment begins with "/*", and ends with "*/", like this:

/*This is a comment*/
p
{
text-align:center;
/*This is another comment*/
color:black;
font-family:arial;
}