Chapter 1

 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

CSS Example

body {
  background-color: lightblue;
}

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

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

CSS Syntax

A CSS rule consists of a selector and a declaration block.

CSS Syntax

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.

Multiple CSS declarations are separated with semicolons, and declaration blocks are surrounded by curly braces.

Example

In this example all

elements will be center-aligned, with a red text color:

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

Example Explained

p is a selector in CSS (it points to the HTML element you want to style:

).

color is a property, and red is the property value

text-align is a property, and center is the property value.

CSS Selectors

A CSS selector selects the HTML element(s) you want to style.

CSS Selectors

CSS selectors are used to "find" (or select) the HTML elements you want to style.

We can divide CSS selectors into five categories:

·         Simple selectors (select elements based on name, id, class)

·         Combinator selectors (select elements based on a specific relationship between them)

·         Pseudo-class selectors (select elements based on a certain state)

·         Pseudo-elements selectors (select and style a part of an element)

·         Attribute selectors (select elements based on an attribute or attribute value)

This page will explain the most basic CSS selectors.

The CSS element Selector

The element selector selects HTML elements based on the element name.

Example

Here, all

elements on the page will be center-aligned, with a red text color: 

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

The CSS id Selector

The id selector uses the id attribute of an HTML element to select a specific element.

The id of an element is 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.

Example

The CSS rule below will be applied to the HTML element with id="para1": 

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

The CSS class Selector

The class selector selects HTML elements with a specific class attribute.

To select elements with a specific class, write a period (.) character, followed by the class name.

Example

In this example all HTML elements with class="center" will be red and center-aligned: 

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

You can also specify that only specific HTML elements should be affected by a class.

Example

In this example only

elements with class="center" will be red and center-aligned: 

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

HTML elements can also refer to more than one class.

Example

In this example the

element will be styled according to class="center" and to class="large": 

<p class="center large">This paragraph refers to two classes.</p>

The CSS Universal Selector

The universal selector (*) selects all HTML elements on the page.

Example

The CSS rule below will affect every HTML element on the page: 

* {
  text-align: center;
  color: blue;
}

The CSS Grouping Selector

The grouping selector selects all the HTML elements with the same style definitions.

Look at the following CSS code (the h1, h2, and p elements have the same style definitions):

h1 {
  text-align: center;
  color: red;
}

h2 {
  text-align: center;
  color: red;
}

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

It will be better to group the selectors, to minimize the code.

To group selectors, separate each selector with a comma.

Example

In this example we have grouped the selectors from the code above: 

h1, h2, p {
  text-align: center;
  color: red;
}

All CSS Simple Selectors