CSS Backgrounds

 The CSS background properties are used to add background effects for elements.

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In these chapters, you will learn about the following CSS background properties:

• background-color
• background-image
• background-repeat
• background-attachment
• background-position
• background (shorthand property)

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CSS background-color

The background-color property specifies the background color of an element.

Example

The background color of a page is set like this:

body {
  background-color: lightblue;
}

Try it Yourself »

With CSS, a color is most often specified by:

• a valid color name - like "red"
• a HEX value - like "#ff0000"
• an RGB value - like "rgb(255,0,0)"

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Other Elements

You can set the background color for any HTML elements:

Example

Here, the <h1>, <p>, and <div> elements will have different background colors: 

h1 {
  background-color: green;
}

div {
  background-color: lightblue;
}

p {
  background-color: yellow;
}

Try it Yourself »

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Opacity / Transparency

The opacity property specifies the opacity/transparency of an element. It can take a value from 0.0 - 1.0. The lower value, the more transparent:

opacity 1

opacity 0.6

opacity 0.3

opacity 0.1

Example

div {
  background-color: green;
  opacity: 0.3;
}

Try it Yourself »

Note: When using the opacity property to add transparency to the background of an element, all of its child elements inherit the same transparency. This can make the text inside a fully transparent element hard to read.

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Transparency using RGBA

If you do not want to apply opacity to child elements, like in our example above, use RGBA color values. The following example sets the opacity for the background color and not the text:

100% opacity

60% opacity

30% opacity

10% opacity

You learned from our CSS Colors Chapter, that you can use RGB as a color value. In addition to RGB, you can use an RGB color value with an alpha channel (RGBA) - which specifies the opacity for a color.

An RGBA color value is specified with: rgba(red, green, blue, alpha). The alpha parameter is a number between 0.0 (fully transparent) and 1.0 (fully opaque).

Example

div {
  background: rgba(0, 128, 0, 0.3) /* Green background with 30% opacity */
}

CSS Color

In CSS, a color can be specified by using a predefined color name:

CSS/HTML support 140 standard color names.

Tomato

Orange

DodgerBlue

MediumSeaGreen

Gray

SlateBlue

Violet

LightGray

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CSS Background Color

You can set the background color for HTML elements:

Hello World

Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat.

Example

<h1 style="background-color:DodgerBlue;">Hello World</h1>
<p style="background-color:Tomato;">Lorem ipsum...</p>

Try it Yourself »

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CSS Text Color

You can set the color of the text:

Hello World

Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat.

Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat.

Example

<h1 style="color:Tomato;">Hello World</h1>
<p style="color:DodgerBlue;">Lorem ipsum...</p>
<p style="color:MediumSeaGreen;">Ut wisi enim...</p>

Try it Yourself »

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CSS Border Color

You can set the color of borders:

Hello World

Hello World

Hello World

Example

<h1 style="border:2px solid Tomato;">Hello World</h1>
<h1 style="border:2px solid DodgerBlue;">Hello World</h1>
<h1 style="border:2px solid Violet;">Hello World</h1>

Try it Yourself »

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CSS Color Values

In CSS, colors can also be specified using RGB values, HEX values, HSL values, RGBA values, and HSLA values:

Same as color name "Tomato":

rgb(255, 99, 71)

#ff6347

hsl(9, 100%, 64%)

Same as color name "Tomato", but 50% transparent:

rgba(255, 99, 71, 0.5)

hsla(9, 100%, 64%, 0.5)

Example

<h1 style="background-color:rgb(255, 99, 71);">...</h1>
<h1 style="background-color:#ff6347;">...</h1>
<h1 style="background-color:hsl(9, 100%, 64%);">...</h1>

<h1 style="background-color:rgba(255, 99, 71, 0.5);">...</h1>
<h1 style="background-color:hsla(9, 100%, 64%, 0.5);">...</h1>

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;
}

Try it Yourself »

You can add comments wherever you want in the code:

Example

p {
  color: red;  /* Set text color to red */
}

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Comments can also span multiple lines: 

Example

/* This is
a multi-line
comment */

p {
  color: red;
}

Try it Yourself »

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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:

Example

<!DOCTYPE html>
<html>
<head>
<style>
p {
  color: red; /* Set text color to red */
}
</style>
</head>
<body>

<h2>My Heading</h2>

<!-- These paragraphs will be red -->
<p>Hello World!</p>
<p>This paragraph is styled with CSS.</p>
<p>CSS comments are not shown in the output.</p>

</body>
</html>

Three Ways to Insert CSS

There are three ways of inserting a style sheet:

• External CSS
• Internal CSS
• Inline CSS

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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 <link> element, inside the head section.

Example

External styles are defined within the <link> element, inside the <head> 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>

Try it Yourself »

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 and the unit (such as margin-left: 20 px;). The correct way is: 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>

Try it Yourself »

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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>

Try it Yourself »

Tip: An inline style loses many of the advantages of a style sheet (by mixing content with presentation). Use this method sparingly.

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Multiple Style Sheets

If some properties have been defined for the same selector (element) in different style sheets, the value from the last read style sheet will be used. 

Assume that an external style sheet has the following style for the <h1> element:

h1 {
  color: navy;
}

Then, assume that an internal style sheet also has the following style for the <h1> element:

h1 {
  color: orange;   
}

Example

If the internal style is defined after the link to the external style sheet, the <h1> elements will be "orange":

<head>
<link rel="stylesheet" type="text/css" href="mystyle.css">
<style>
h1 {
  color: orange;
}
</style>
</head>

Try it Yourself »

Example

However, if the internal style is defined before the link to the external style sheet, the <h1> elements will be "navy": 

<head>
<style>
h1 {
  color: orange;
}
</style>
<link rel="stylesheet" type="text/css" href="mystyle.css">
</head>

Try it Yourself »

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Cascading Order

What style will be used when there is more than one style specified for an HTML element?

All the styles in a page will "cascade" into a new "virtual" style sheet by the following rules, where number one has the highest priority:

1. Inline style (inside an HTML element)
2. External and internal style sheets (in the head section)
3. Browser default

So, an inline style has the highest priority and will override external and internal styles and browser defaults.

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;
}

Try it Yourself »

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

Try it Yourself »

HTML elements can also refer to more than one class.

Example

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>

Try it Yourself »

Note: A class name cannot start with a number!

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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;
}

Try it Yourself »

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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;
}

Try it Yourself »

All CSS Simple Selectors

Selector	Example	Example description
#id	#firstname	Selects the element with id="firstname"
.class	.intro	Selects all elements with class="intro"
element.class	p.intro	Selects only <p> elements with class="intro"
*	*	Selects all elements
element	p	Selects all <p> elements
element,element,..	div, p	Selects all <div> elements and all <p> elements