3 KiB
status: #doc Tags: #html #css links: html-css Date: 2023-08-01
css selector
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.
Here, all <p> elements on the page will be center-aligned, with a red text color:
p { text-align: center;
color: red;}
```
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## 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!
```css
#para1 { text-align: center;
color: red;}
Note: An id name cannot start with a number!
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.
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.
p.center { text-align: center;
color: red;}
HTML elements can also refer to more than one class.
In this example the <p> element will be styled according to class="center" and to class="large":
<p class="center large">This paragraph refers to two classes.</p>
Note: A class name cannot start with a number!
The CSS Universal Selector
The universal selector (*) selects all HTML elements on the page.
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.
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;}
we have grouped the selectors from the code above:
h1, h2, p { text-align: center;
color: red;}