CSS is the language we use to style an HTML document.
CSS describes how HTML elements should be displayed.
This tutorial will teach you CSS from basic to advanced.
Example in Each Section
This CSS tutorial contains hundreds of CSS examples.
With our online editor, you can edit the CSS, and click on a button to view the
result.
Example
body {
background-color: lightblue;
}
h1 {
color: white;
text-align: center;
}
p {
font-family: verdana;
font-size: 20px;
}
Click on the "Try it Yourself" button to see how it works.
CSS Introduction
CSS is the language we use to style a Web page.
What is CSS?
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 is used to define styles for your web pages, including the design, layout and
variations in display for different devices and screen sizes.
Example
body {
background-color: lightblue;
}
h1 {
color: white;
text-align: center;
}
p {
font-family: verdana;
font-size: 20px;
}
CSS Solved a Big Problem
HTML was NEVER intended to contain tags for formatting a web page!
HTML was created to describe the content of a web page, 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
websites, 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.
CSS removed the style formatting from the HTML page!
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
p { color: red;; text-align:
center; }
Example Explained
p is a selector in CSS (it points to the
HTML element you want to style: <p>).
color is a property, and red is the property value
text-align is a property, and center is the property value
CSS SELECTOR
A CSS selector selects the HTML element(s) you want to style.
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)
The CSS element Selector
The element selector selects HTML elements based on the element name.
Example
Here, all <p> 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
The CSS rule below will be applied to the HTML element with id="para1":
.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<p> elements with class="center" will be red and
center-aligned:
<p class="center"> {
text-align: center;
color: red;
}
</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):
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
In this example we have grouped the selectors from the code above:
h1, h2, p {
text-align: center;
color: red;
}
How TO Add CSS
When a browser reads a style sheet, it will format the HTML document according to the
information in the style sheet.
Three Ways to Insert CSS
There are three ways of inserting a style sheet:
External css
internal css
inline css
External CSS
With an external style sheet, you can change the look of an entire website by
changing just one file!
Each HTML page must include a reference to the external style sheet file inside the
element, inside the head section.
Example
External styles are defined within the
element, inside the
section of an HTML page:
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="mystyle.css">
</head>
<body>
<h1>This is a heading</h1>
<p>This is a paragraph.</p>
</body>
</html>
An external style sheet can be written in any text editor, and must be saved with a
.css extension.
The external .css file should not contain any HTML tags.
Here is how the mystyle.css file looks:
"mystyle.css"
body {
background-color: lightblue;
}
h1 {
color: navy;
margin-left: 20px;
}
Note: Do not add a space between the property value (20) and the unit (px):
Incorrect (space): margin-left: 20 px;
Correct (no space): margin-left: 20px;
Internal CSS
An internal style sheet may be used if one single HTML page has a unique style.
The internal style is defined inside the <style> element, inside the head
section.
Example
Internal styles are defined within the <style> element, inside the
<head> section of an HTML page:
<!DOCTYPE html>
<html>
<head>
<style>
body {
background-color: linen;
}
h1 {
color: maroon;
margin-left: 40px;
}
</style>
</head>
<body>
<h1>This is a heading</h1>
<p>This is a paragraph.</p>
</body>
</html>
Inline CSS
An inline style may be used to apply a unique style for a single element.
To use inline styles, add the style attribute to the relevant element. The style
attribute can contain any CSS property.
Example
Inline styles are defined within the "style" attribute of the relevant element:
<!DOCTYPE html>
<html>
<body>
<h1 style="color:blue;text-align:center;">This is a
heading</h1>
<p style="color:red;">This is a paragraph.</p>
</body>
</html>
CSS Comments
CSS comments are not displayed in the browser, but they can help document your source code.
CSS Comments
Comments are used to explain the code, and may help when you edit the source code at a
later date.
Comments are ignored by browsers.
A CSS comment is placed inside the <style > element, and starts with /* and ends
with */:
Example
/* This is a single-line comment */
p { color: red; }
You can add comments wherever you want in the code:
Example
p { color: red; /* Set text color to red */ }
Comments can also span multiple lines:
Example
/* This is
a multi-line
comment */
p { color: red; }
HTML and CSS Comments
From the HTML tutorial, you learned that you can add comments to your HTML source by using the syntax.
In the following example, we use a combination of HTML and CSS comments:
CSS Comments
CSS comments are not displayed in the browser, but they can help document your source code.
CSS Comments
Example
color: red;
}
You can add comments wherever you want in the code:
Example
color: red; /* Set text color to red */
}
Comments can also span multiple lines:
Example
a multi-line
comment */
color: red;
}
HTML and CSS Comments
Example