In this section

• Introduction
• Why use CSS?
• CSS Syntax
• CSS Selector

CSS Introduction

• CSS stands for Cascading Style Sheets.
• CSS describes how HTML elements are to be displayed on screen, paper, or in other media.
• CSS saves a lot of work. It can control the layout of multiple web pages all at once External stylesheets are stored in CSS files.

Why Use CSS?

• CSS saves time :
You can write CSS once and reuse same sheet in multiple HTML pages.
• Easy Maintainence :
To make a global change simply change the style, and all elements in all the webpages will be updated automatically.
• Search Engines :
CSS is considered as clean coding technique, which means search engines won’t have to struggle to “read” its content.
• Superior styles to HTML :
CSS has a much wider array of attributes than HTML, so you can give a far better look to your HTML page in comparison to HTML attributes.
• Offline Browsing :
CSS can store web applications locally with the help of offline catche.Using of this we can view offline websites.
• CSS is used to define styles for your web pages, including the design, layout and variations in display for different devices and screen sizes.

CSS Syntax

• A CSS comprises of style rules that are interpreted by the browser and then applied to the corresponding elements in your document.
• A style rule set consists of a selector and declaration block.

Selector => p
declaration => {color:blue, font-size:12px;}

• The selector points to the HTML element you want to style.
• The declaration block contains one or more declarations separated by semicolons.
• Each declaration includes a CSS property name and a value, separated by a colon.
For Example: -> color is property and blue is value. -> font size is property and 12px is value.
• A CSS declaration always ends with a semicolon, and declaration blocks are surrounded by curly braces.


Example: body { background-color: lightblue; },

h1 { color: white; text-align: center; },

p { font-family: verdana; font-size: 20px; }


• CSS Saves a Lot of Work!


• The style definitions are normally saved in external .css files. With an external stylesheet file, you can change the look of an entire website by changing just one file!

CSS Seclector

1. The Universal Selector: Rather than selecting elements of a specific type, the universal selector quite simply matches the name of any element type.
Ex.

           *{
                color: red;
            }
            

2. The Element Selector: : The element selector selects elements based on the element name. You can select all p elements on a page like this (in this case, all p elements will be center-aligned, with a red text color).
EX.

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

3. The Descending Selector:Suppose you want to apply a style rule to a particular element only when it lies inside a particular element. As given in the following example, style rule will apply to em element only when it lies inside ul tag.
EX.

           ul em { 
                color: #000000;  
            }            

4. The Id selector:
• The id selector uses the id attribute of an HTML element to select a specific element.
• The id of an element should be unique within a page, so the id selector is used to select one unique element!
• To select an element with a specific id, write a hash (#) character, followed by the id of the element.
• The style rule below will be applied to the HTML element with id=”para1″:

           #para1 { 
                text-align: center; 
                color: red; 
            }

5. The Class Selector:
• The class selector selects elements with a specific class attribute.
• To select elements with a specific class, write a period (.) character, followed by the name of the class.
• In the example below, all HTML elements with class=”center” will be red and center-aligned:

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