CSS Selectors

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

The CSS element Selector

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

Example:

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:

#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:

.center {

  text-align: center;

  color: red;

}

We can also specify this content

p.center {

  text-align: center;

  color: red;

}

HTML elements can also refer to more than one class.

Example: 

<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.

* {

  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):

Example:

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:

Group Selection

h1, h2, p {

  text-align: center;

  color: red;

}