Friday, January 2, 2009

CSS Tutorial 2


What is CSS?

  • CSS stands for Cascading Style Sheets
  • Styles define how to display HTML elements
  • Styles are normally stored in Style Sheets
  • Styles were added to HTML 4.0 to solve a problem
  • External Style Sheets can save you a lot of work
  • External Style Sheets are stored in CSS files
  • Multiple style definitions will cascade into one

CSS Demo

With CSS, your HTML documents can be displayed using different output styles:

See how it works


Styles Solve a Common Problem

HTML tags were originally designed to define the content of a document. They were supposed to say "This is a header", "This is a paragraph", "This is a table", by using tags like

,

,

, and so on. The layout of the document was supposed to be taken care of by the browser, without using any formatting tags.

As the two major browsers - Netscape and Internet Explorer - continued to add new HTML tags and attributes (like the tag and the color attribute) to the original HTML specification, it became more and more difficult to create Web sites where the content of HTML documents was clearly separated from the document's presentation layout.

To solve this problem, the World Wide Web Consortium (W3C) - the non profit, standard setting consortium, responsible for standardizing HTML - created STYLES in addition to HTML 4.0.

All major browsers support Cascading Style Sheets.


Style Sheets Can Save a Lot of Work

Styles sheets define HOW HTML elements are to be displayed, just like the font tag and the color attribute in HTML 3.2. Styles are normally saved in external .css files. External style sheets enable you to change the appearance and layout of all the pages in your Web, just by editing one single CSS document!

CSS is a breakthrough in Web design because it allows developers to control the style and layout of multiple Web pages all at once. As a Web developer you can define a style for each HTML element and apply it to as many Web pages as you want. To make a global change, simply change the style, and all elements in the Web are updated automatically.


Multiple Styles Will Cascade Into One

Style sheets allow style information to be specified in many ways. Styles can be specified inside a single HTML element, inside the element of an HTML page, or in an external CSS file. Even multiple external style sheets can be referenced inside a single HTML document.

Cascading Order

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

Generally speaking we can say that all the styles will "cascade" into a new "virtual" style sheet by the following rules, where number four has the highest priority:

  1. Browser default
  2. External style sheet
  3. Internal style sheet (inside the tag)
  4. Inline style (inside an HTML element)

So, an inline style (inside an HTML element) has the highest priority, which means that it will override a style declared inside the tag, in an external style sheet, or in a browser (a default value).


Syntax

The CSS syntax is made up of three parts: a selector, a property and a value:

selector {property: value}

The selector is normally the HTML element/tag you wish to define, the property is the attribute you wish to change, and each property can take a value. The property and value are separated by a colon, and surrounded by curly braces:

body {color: black}

Note: If the value is multiple words, put quotes around the value:

p {font-family: "sans serif"}

Note: If you wish to specify more than one property, you must separate each property with a semicolon. The example below shows how to define a center aligned paragraph, with a red text color:

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

To make the style definitions more readable, you can describe one property on each line, like this:

p
{
text-align: center;
color: black;
font-family: arial
}


Grouping

You can group selectors. Separate each selector with a comma. In the example below we have grouped all the header elements. All header elements will be displayed in green text color:

h1,h2,h3,h4,h5,h6 
{
color: green
}


The class Selector

With the class selector you can define different styles for the same type of HTML element.

Say that you would like to have two types of paragraphs in your document: one right-aligned paragraph, and one center-aligned paragraph. Here is how you can do it with styles:

p.right {text-align: right}
p.center {text-align: center}

You have to use the class attribute in your HTML document:

This paragraph will be right-aligned.

This paragraph will be center-aligned.

Note: Only one class attribute can be specified per HTML element! The example below is wrong:

This is a paragraph.

You can also omit the tag name in the selector to define a style that will be used by all HTML elements that have a certain class. In the example below, all HTML elements with class="center" will be center-aligned:

.center {text-align: center}

In the code below both the h1 element and the p element have class="center". This means that both elements will follow the rules in the ".center" selector:

This heading will be center-aligned

This paragraph will also be center-aligned.

RemarkDo NOT start a class name with a number! It will not work in Mozilla/Firefox.


The id Selector

You can also define styles for HTML elements with the id selector. The id selector is defined as a #.

The style rule below will match the element that has an id attribute with a value of "green":

#green {color: green}

The style rule below will match the p element that has an id with a value of "para1":

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

RemarkDo NOT start an ID name with a number! It will not work in Mozilla/Firefox.


CSS Comments

Comments are used to explain your code, and may help you when you edit the source code at a later date. A comment will be ignored by browsers. A CSS comment begins with "/*", and ends with "*/", like this:

/* This is a comment */
p
{
text-align: center;
/* This is another comment */
color: black;
font-family: arial
}

Examples


How to Insert a Style Sheet

When a browser reads a style sheet, it will format the document according to it. There are three ways of inserting a style sheet:

External Style Sheet

An external style sheet is ideal when the style is applied to many pages. With an external style sheet, you can change the look of an entire Web site by changing one file. Each page must link to the style sheet using the tag. The tag goes inside the head section:

href="mystyle.css" />

The browser will read the style definitions from the file mystyle.css, and format the document according to it.

An external style sheet can be written in any text editor. The file should not contain any html tags. Your style sheet should be saved with a .css extension. An example of a style sheet file is shown below:

hr {color: sienna}
p {margin-left: 20px}
body {background-image: url("images/back40.gif")}

RemarkDo NOT leave spaces between the property value and the units! If you use "margin-left: 20 px" instead of "margin-left: 20px" it will only work properly in IE6 but it will not work in Mozilla/Firefox or Netscape.

Internal Style Sheet

An internal style sheet should be used when a single document has a unique style. You define internal styles in the head section by using the

     

The browser will now read the style definitions, and format the document according to it.

Note: A browser normally ignores unknown tags. This means that an old browser that does not support styles, will ignore the

     

Inline Styles

An inline style loses many of the advantages of style sheets by mixing content with presentation. Use this method sparingly, such as when a style is to be applied to a single occurrence of an element.

To use inline styles you use the style attribute in the relevant tag. The style attribute can contain any CSS property. The example shows how to change the color and the left margin of a paragraph:

This is a paragraph


Multiple Style Sheets

If some properties have been set for the same selector in different style sheets, the values will be inherited from the more specific style sheet.

For example, an external style sheet has these properties for the h3 selector:

h3 
{
color: red;
text-align: left;
font-size: 8pt
}

And an internal style sheet has these properties for the h3 selector:

h3 
{
text-align: right; 
font-size: 20pt
}

If the page with the internal style sheet also links to the external style sheet the properties for h3 will be:

color: red; 
text-align: right; 
font-size: 20pt

The color is inherited from the external style sheet and the text-alignment and the font-size is replaced by the internal style sheet.

Examples

Set the background color
This example demonstrates how to set the background color for an element.

Set an image as the background
This example demonstrates how to set an image as the background.

How to repeat a background image
This example demonstrates how to repeat a background image only vertically.

How to place the background image
This example demonstrates how to place the image on the page.

How to set a fixed background image
This example demonstrates how to set a fixed background image. The image will not scroll with the rest of the page.

All the background properties in one declaration
This example demonstrates how to use the shorthand property for setting all of the background properties in one declaration.

CSS Background Properties

The CSS background properties allow you to control the background color of an element, set an image as the background, repeat a background image vertically or horizontally, and position an image on a page.

Browser support: IE: Internet Explorer, F: Firefox, N: Netscape.

W3C: The number in the "W3C" column indicates in which CSS recommendation the property is defined (CSS1 or CSS2).

Property

Description

Values

IE

F

N

W3C

background

A shorthand property for setting all background properties in one declaration

background-color
background-image
background-repeat background-attachment background-position

4

1

6

1

background-attachment

Sets whether a background image is fixed or scrolls with the rest of the page

scroll
fixed

4

1

6

1

background-color

Sets the background color of an element

color-rgb
color-hex
color-name
transparent

4

1

4

1

background-image

Sets an image as the background

url
none

4

1

4

1

background-position

Sets the starting position of a background image

top left
top center
top right
center left
center center
center right
bottom left
bottom center
bottom right
x-% y-%
x-pos y-pos

4

1

6

1

background-repeat

Sets if/how a background image will be repeated

repeat
repeat-x
repeat-y
no-repeat

4

1

4

1

The CSS text properties define the appearance of text.


Examples

Set the color of the text
This example demonstrates how to set the color of the text.

Set the background-color of the text
This example demonstrates how to set the background-color of a part of the text.

Specify the space between characters
This example demonstrates how to increase or decrease the space between characters.

Align the text
This example demonstrates how to align the text.

Decorate the text
This example demonstrates how to add decoration to text.

Indent text
This example demonstrates how to indent the first line of a paragraph.

Control the letters in a text
This example demonstrates how to control the letters in a text.


CSS Text Properties

The CSS text properties allow you to control the appearance of text. It is possible to change the color of a text, increase or decrease the space between characters in a text, align a text, decorate a text, indent the first line in a text, and more.

Browser support: IE: Internet Explorer, F: Firefox, N: Netscape.

W3C: The number in the "W3C" column indicates in which CSS recommendation the property is defined (CSS1 or CSS2).

Property

Description

Values

IE

F

N

W3C

color

Sets the color of a text

color

3

1

4

1

direction

Sets the text direction

ltr
rtl

6

1

6

2

letter-spacing

Increase or decrease the space between characters

normal
length

4

1

6

1

text-align

Aligns the text in an element

left
right
center
justify

4

1

4

1

text-decoration

Adds decoration to text

none
underline
overline
line-through
blink

4

1

4

1

text-indent

Indents the first line of text in an element

length
%

4

1

4

1

text-shadow

none
color
length

text-transform

Controls the letters in an element

none
capitalize
uppercase
lowercase

4

1

4

1

unicode-bidi

normal
embed
bidi-override

5

2

white-space

Sets how white space inside an element is handled

normal
pre
nowrap

5

1

4

1

word-spacing

Increase or decrease the space between words

normal
length

6

1

6

1

The CSS font properties define the font in text.


Examples

Set the font of a text
This example demonstrates how to set a font of a text.

Set the size of the font
This example demonstrates how to set the size of a font.

Set the style of the font
This example demonstrates how to set the style of a font.

Set the variant of the font
This example demonstrates how to set the variant of a font.

Set the boldness of the font
This example demonstrates how to set the boldness of a font.

All the font properties in one declaration
This example demonstrates how to use the shorthand property for setting all of the font properties in one declaration.


CSS Font Properties

The CSS font properties allow you to change the font family, boldness, size, and the style of a text.

Note: In CSS1 fonts are identified by a font name. If a browser does not support the specified font, it will use a default font.

Browser support: IE: Internet Explorer, F: Firefox, N: Netscape.

W3C: The number in the "W3C" column indicates in which CSS recommendation the property is defined (CSS1 or CSS2).

Property

Description

Values

IE

F

N

W3C

font

A shorthand property for setting all of the properties for a font in one declaration

font-style
font-variant
font-weight
font-size/line-height
font-family
caption
icon
menu
message-box
small-caption
status-bar

4

1

4

1

font-family

A prioritized list of font family names and/or generic family names for an element

family-name
generic-family

3

1

4

1

font-size

Sets the size of a font

xx-small
x-small
small
medium
large
x-large
xx-large
smaller
larger
length
%

3

1

4

1

font-size-adjust

Specifies an aspect value for an element that will preserve the x-height of the first-choice font

none
number

-

-

-

2

font-stretch

Condenses or expands the current font-family

normal
wider
narrower
ultra-condensed
extra-condensed
condensed
semi-condensed
semi-expanded
expanded
extra-expanded
ultra-expanded

-

-

-

2

font-style

Sets the style of the font

normal
italic
oblique

4

1

4

1

font-variant

Displays text in a small-caps font or a normal font

normal
small-caps

4

1

6

1

font-weight

Sets the weight of a font

normal
bold
bolder
lighter
100
200
300
400
500
600
700
800
900

4

1

4

1

The CSS border properties define the borders around an element.


Examples

Set the style of the four borders
This example demonstrates how to set the style of the four borders.

Set different borders on each side
This example demonstrates how to set different borders on each side of the element.

Set the color of the four borders
This example demonstrates how to set the color of the four borders. It can have from one to four colors.

Set the width of the bottom border
This example demonstrates how to set the width of the bottom border.

Set the width of the left border
This example demonstrates how to set the width of the left border.

Set the width of the right border
This example demonstrates how to set the width of the right border.

Set the width of the top border
This example demonstrates how to set the width of the top border.

All the bottom border properties in one declaration
This example demonstrates a shorthand property for setting all of the properties for the bottom border in one declaration.

All the left border properties in one declaration
This example demonstrates a shorthand property for setting all of the properties for the left border in one declaration.

All the right border properties in one declaration
This example demonstrates a shorthand property for setting all of the properties for the right border in one declaration.

All the top border properties in one declaration
This example demonstrates a shorthand property for setting all of the properties for the top border in one declaration.

All the width of the border properties in one declaration
This example demonstrates a shorthand property for setting the width of the four borders in one declaration, can have from one to four values.

All the border properties in one declaration
This example demonstrates a shorthand property for setting all of the properties for the four borders in one declaration, can have from one to three values.


CSS Border Properties

The CSS border properties allow you to specify the style and color of an element's border. In HTML we use tables to create borders around a text, but with the CSS border properties we can create borders with nice effects, and it can be applied to any element.

Browser support: IE: Internet Explorer, F: Firefox, N: Netscape.

W3C: The number in the "W3C" column indicates in which CSS recommendation the property is defined (CSS1 or CSS2).

Property

Description

Values

IE

F

N

W3C

border

A shorthand property for setting all of the properties for the four borders in one declaration

border-width
border-style
border-color

4

1

4

1

border-bottom

A shorthand property for setting all of the properties for the bottom border in one declaration

border-bottom-width
border-style
border-color

4

1

6

1

border-bottom-color

Sets the color of the bottom border

border-color

4

1

6

2

border-bottom-style

Sets the style of the bottom border

border-style

4

1

6

2

border-bottom-width

Sets the width of the bottom border

thin
medium
thick
length

4

1

4

1

border-color

Sets the color of the four borders, can have from one to four colors

color

4

1

6

1

border-left

A shorthand property for setting all of the properties for the left border in one declaration

border-left-width
border-style
border-color

4

1

6

1

border-left-color

Sets the color of the left border

border-color

4

1

6

2

border-left-style

Sets the style of the left border

border-style

4

1

6

2

border-left-width

Sets the width of the left border

thin
medium
thick
length

4

1

4

1

border-right

A shorthand property for setting all of the properties for the right border in one declaration

border-right-width
border-style
border-color

4

1

6

1

border-right-color

Sets the color of the right border

border-color

4

1

6

2

border-right-style

Sets the style of the right border

border-style

4

1

6

2

border-right-width

Sets the width of the right border

thin
medium
thick
length

4

1

4

1

border-style

Sets the style of the four borders, can have from one to four styles

none
hidden
dotted
dashed
solid
double
groove
ridge
inset
outset

4

1

6

1

border-top

A shorthand property for setting all of the properties for the top border in one declaration

border-top-width
border-style
border-color

4

1

6

1

border-top-color

Sets the color of the top border

border-color

4

1

6

2

border-top-style

Sets the style of the top border

border-style

4

1

6

2

border-top-width

Sets the width of the top border

thin
medium
thick
length

4

1

4

1

border-width

A shorthand property for setting the width of the four borders in one declaration, can have from one to four values

thin
medium
thick
length

4

1

4

1


The CSS margin properties define the space around elements.


Examples

Set the left margin of a text
This example demonstrates how to set the left margin of a text.

Set the right margin of a text
This example demonstrates how to set the right margin of a text.

Set the top margin of a text
This example demonstrates how to set the top margin of a text.

Set the bottom margin of a text
This example demonstrates how to set the bottom margin of a text.

All the margin properties in one declaration
This example demonstrates how to set a shorthand property for setting all of the margin properties in one declaration.


CSS Margin Properties

The CSS margin properties define the space around elements. It is possible to use negative values to overlap content. The top, right, bottom, and left margin can be changed independently using separate properties. A shorthand margin property can also be used to change all of the margins at once.

Note: Netscape and IE give the body tag a default margin of 8px. Opera does not! Instead, Opera applies a default padding of 8px, so if one wants to adjust the margin for an entire page and have it display correctly in Opera, the body padding must be set as well!

Browser support: IE: Internet Explorer, F: Firefox, N: Netscape.

W3C: The number in the "W3C" column indicates in which CSS recommendation the property is defined (CSS1 or CSS2).

Property

Description

Values

IE

F

N

W3C

margin

A shorthand property for setting the margin properties in one declaration

margin-top
margin-right
margin-bottom
margin-left

4

1

4

1

margin-bottom

Sets the bottom margin of an element

auto
length
%

4

1

4

1

margin-left

Sets the left margin of an element

auto
length
%

3

1

4

1

margin-right

Sets the right margin of an element

auto
length
%

3

1

4

1

margin-top

Sets the top margin of an element

auto
length
%

3

1

4

1


The CSS padding properties define the space between the element border and the element content.


Examples

Set the left padding
This example demonstrates how to set the left padding of a tablecell.

Set the right padding
This example demonstrates how to set the right padding of a tablecell.

Set the top padding
This example demonstrates how to set the top padding of a tablecell.

Set the bottom padding
This example demonstrates how to set the bottom padding of a tablecell.

All the padding properties in one declaration
This example demonstrates a shorthand property for setting all of the padding properties in one declaration, can have from one to four values.


CSS Padding Properties

The CSS padding properties define the space between the element border and the element content. Negative values are not allowed. The top, right, bottom, and left padding can be changed independently using separate properties. A shorthand padding property is also created to control multiple sides at once.

Browser support: IE: Internet Explorer, F: Firefox, N: Netscape.

W3C: The number in the "W3C" column indicates in which CSS recommendation the property is defined (CSS1 or CSS2).

Property

Description

Values

IE

F

N

W3C

padding

A shorthand property for setting all of the padding properties in one declaration

padding-top
padding-right
padding-bottom
padding-left

4

1

4

1

padding-bottom

Sets the bottom padding of an element

length
%

4

1

4

1

padding-left

Sets the left padding of an element

length
%

4

1

4

1

padding-right

Sets the right padding of an element

length
%

4

1

4

1

padding-top

Sets the top padding of an element

length
%

4

1

4

1


The CSS list properties allow you to place the list-item marker, change between different list-item markers, or set an image as the list-item marker.


Examples

The different list-item markers in unordered lists
This example demonstrates the different list-item markers in CSS.

The different list-item markers in ordered lists
This example demonstrates the different list-item markers in CSS.

Set an image as the list-item marker
This example demonstrates how to set an image as the list-item marker.

Place the list-item marker
This example demonstrates where to place the list-item marker.

All list properties in one declaration
This example demonstrates a shorthand property for setting all of the properties for a list in one declaration.


CSS List Properties

The CSS list properties allow you to place the list-item marker, change between different list-item markers, or set an image as the list-item marker.

Browser support: IE: Internet Explorer, F: Firefox, N: Netscape.

W3C: The number in the "W3C" column indicates in which CSS recommendation the property is defined (CSS1 or CSS2).

Property

Description

Values

IE

F

N

W3C

list-style

A shorthand property for setting all of the properties for a list in one declaration

list-style-type
list-style-position
list-style-image

4

1

6

1

list-style-image

Sets an image as the list-item marker

none
url

4

1

6

1

list-style-position

Sets where the list-item marker is placed in the list

inside
outside

4

1

6

1

list-style-type

Sets the type of the list-item marker

none
disc
circle
square
decimal
decimal-leading-zero
lower-roman
upper-roman
lower-alpha
upper-alpha
lower-greek
lower-latin
upper-latin
hebrew
armenian
georgian
cjk-ideographic
hiragana
katakana
hiragana-iroha
katakana-iroha

4

1

4

1

marker-offset

auto
length

1

7

2

The CSS dimension properties allow you to control the height and width of an element. It also allows you to increase the space between two lines.


Examples

Increase the space between lines
This example demonstrates how to increase the space between the lines.


CSS Dimension Properties

The CSS dimension properties allow you to control the height and width of an element. It also allows you to increase the space between two lines.

Browser support: IE: Internet Explorer, F: Firefox, N: Netscape.

W3C: The number in the "W3C" column indicates in which CSS recommendation the property is defined (CSS1 or CSS2).

Property

Description

Values

IE

F

N

W3C

height

Sets the height of an element

auto
length
%

4

1

6

1

line-height

Sets the distance between lines

normal
number
length
%

4

1

4

1

max-height

Sets the maximum height of an element

none
length
%

-

1

6

2

max-width

Sets the maximum width of an element

none
length
%

-

1

6

2

min-height

Sets the minimum height of an element

length
%

-

1

6

2

min-width

Sets the minimum width of an element

length
%

-

1

6

2

width

Sets the width of an element

auto
%
length

4

1

4

1


The CSS classification properties allow you to specify how and where to display an element.


Examples

How to display an element
This example demonstrates how to display an element.

A simple use of the float property
Let an image float to the right in a paragraph.

An image with border and margins that floats to the right in a paragraph
Let an image float to the right in a paragraph. Add border and margins to the image.

An image with a caption that floats to the right
Let an image with a caption float to the right.

Let the first letter of a paragraph float to the left
Let the first letter of a paragraph float to the left and style the letter.

Creating a horizontal menu
Use float with a list of hyperlinks to create a horizontal menu.

Creating a homepage without tables
Use float to create a homepage with a header, footer, left content and main content.

Position:relative
This example demonstrates how to position an element relative to its normal position.

Position:absolute
This example demonstrates how to position an element using an absolute value.

How to make an element invisible
This example demonstrates how to make an element invisible. Do you want the element to show or not?

Change the cursor
This example demonstrates how to change the cursor.


CSS Classification Properties

The CSS classification properties allow you to control how to display an element, set where an image will appear in another element, position an element relative to its normal position, position an element using an absolute value, and how to control the visibility of an element.

Browser support: IE: Internet Explorer, F: Firefox, N: Netscape.

W3C: The number in the "W3C" column indicates in which CSS recommendation the property is defined (CSS1 or CSS2).

Property

Description

Values

IE

F

N

W3C

clear

Sets the sides of an element where other floating elements are not allowed

left
right
both
none

4

1

4

1

cursor

Specifies the type of cursor to be displayed

url
auto
crosshair
default
pointer
move
e-resize
ne-resize
nw-resize
n-resize
se-resize
sw-resize
s-resize
w-resize
text
wait
help

4

1

6

2

display

Sets how/if an element is displayed

none
inline
block
list-item
run-in
compact
marker
table
inline-table
table-row-group
table-header-group
table-footer-group
table-row
table-column-group
table-column
table-cell
table-caption

4

1

4

1

float

Sets where an image or a text will appear in another element

left
right
none

4

1

4

1

position

Places an element in a static, relative, absolute or fixed position

static
relative
absolute
fixed

4

1

4

2

visibility

Sets if an element should be visible or invisible

visible
hidden
collapse

4

1

6

2


The CSS positioning properties allows you to position an element.


Examples

Position:relative
This example demonstrates how to position an element relative to its normal position.

Position:absolute
This example demonstrates how to position an element using an absolute value.

Set the shape of an element
This example demonstrates how to set the shape of an element. The element is clipped into this shape, and displayed.

Overflow
This example demonstrates how to set the overflow property to specify what should happen when an element's content is too big to fit in a specified area.

Vertical align an image
This example demonstrates how to vertical align an image in a text.

Z-index
Z-index can be used to place an element "behind" another element.

Z-index
The elements in the example above have now changed their Z-index.


CSS Positioning Properties

The CSS positioning properties allow you to specify the left, right, top, and bottom position of an element. It also allows you to set the shape of an element, place an element behind another, and to specify what should happen when an element's content is too big to fit in a specified area.

Browser support: IE: Internet Explorer, F: Firefox, N: Netscape.

W3C: The number in the "W3C" column indicates in which CSS recommendation the property is defined (CSS1 or CSS2).

Property

Description

Values

IE

F

N

W3C

bottom

Sets how far the bottom edge of an element is above/below the bottom edge of the parent element

auto
%
length

5

1

6

2

clip

Sets the shape of an element. The element is clipped into this shape, and displayed

shape
auto

4

1

6

2

left

Sets how far the left edge of an element is to the right/left of the left edge of the parent element

auto
%
length

4

1

4

2

overflow

Sets what happens if the content of an element overflow its area

visible
hidden
scroll
auto

4

1

6

2

position

Places an element in a static, relative, absolute or fixed position

static
relative
absolute
fixed

4

1

4

2

right

Sets how far the right edge of an element is to the left/right of the right edge of the parent element

auto
%
length

5

1

6

2

top

Sets how far the top edge of an element is above/below the top edge of the parent element

auto
%
length

4

1

4

2

vertical-align

Sets the vertical alignment of an element

baseline
sub
super
top
text-top
middle
bottom
text-bottom
length

%

4

1

4

1

z-index

Sets the stack order of an element

auto
number

4

1

6

2


CSS pseudo-classes are used to add special effects to some selectors.


Examples

Hyperlink
This example demonstrates how to add different colors to a hyperlink in a document.

Hyperlink 2
This example demonstrates how to add other styles to hyperlinks.

:first-child (does not work in IE)
This example demonstrates the use of the :first-child pseudo-class.

:lang (does not work in IE)
This example demonstrates the use of the :lang pseudo-class.


Syntax

The syntax of pseudo-classes:

selector:pseudo-class {property: value}

CSS classes can also be used with pseudo-classes:

selector.class:pseudo-class {property: value}


Anchor Pseudo-classes

A link that is active, visited, unvisited, or when you mouse over a link can all be displayed in different ways in a CSS-supporting browser:

a:link {color: #FF0000}     /* unvisited link */
a:visited {color: #00FF00}  /* visited link */
a:hover {color: #FF00FF}   /* mouse over link */
a:active {color: #0000FF}   /* selected link */

Note: a:hover MUST come after a:link and a:visited in the CSS definition in order to be effective!!

Note: a:active MUST come after a:hover in the CSS definition in order to be effective!!

Note: Pseudo-class names are not case-sensitive.


Pseudo-classes and CSS Classes

Pseudo-classes can be combined with CSS classes:

a.red:visited {color: #FF0000}
CSS Syntax

If the link in the example above has been visited, it will be displayed in red.


CSS2 - The :first-child Pseudo-class

The :first-child pseudo-class matches a specified element that is the first child of another element.

In this example, the selector matches any p element that is the first child of a div element, and indents the first paragraph inside a div element:

div > p:first-child
{
text-indent:25px
}

This selector will match the first paragraph inside the div in the following HTML:

First paragraph in div.
This paragraph will be indented.

Second paragraph in div.
This paragraph will not be indented.

   

but it will not match the paragraph in this HTML:

Header

The first paragraph inside the div.
This paragraph will not be indented.

In this example, the selector matches any em element that is the first child of a p element, and sets the font-weight to bold for the first em inside a p element:

p:first-child em
{
font-weight:bold
}

For example, the em in the HTML below is the first child of the paragraph:

I am a strong man.

In this example, the selector matches any a element that is the first child of any element, and sets the text-decoration to none:

a:first-child
{
text-decoration:none
}

For example, the first a in the HTML below is the first child of the paragraph and will not be underlined. But the second a in the paragraph is not the first child of the paragraph and will be underlined:

Visit W3Schools
and learn CSS!
Visit W3Schools
and learn HTML!


CSS2 - The :lang Pseudo-class

The :lang pseudo-class allows you to define special rules for different languages. In the example below, the :lang class defines the type of quotation marks for q elements with a lang attribute with a value of "no":

Some text A quote in a paragraph

Some text.


Pseudo-classes

Browser support: IE: Internet Explorer, F: Firefox, N: Netscape.

W3C: The number in the "W3C" column indicates in which CSS recommendation the property is defined (CSS1 or CSS2).

Pseudo-class

Purpose

IE

F

N

W3C

:active

Adds special style to an activated element

4

1

8

1

:focus

Adds special style to an element while the element has focus

-

-

-

2

:hover

Adds special style to an element when you mouse over it

4

1

7

1

:link

Adds special style to an unvisited link

3

1

4

1

:visited

Adds special style to a visited link

3

1

4

1

:first-child

Adds special style to an element that is the first child of some other element

1

7

2

:lang

Allows the author to specify a language to use in a specified element

1

8

2


CSS pseudo-elements are used to add special effects to some selectors.


Examples

Make the first letter special
This example demonstrates how to add a special effect to the first letter of a text.

Make the first line special
This example demonstrates how to add a special effect to the first line of a text.


Syntax

The syntax of pseudo-elements:

selector:pseudo-element {property: value}

CSS classes can also be used with pseudo-elements:

selector.class:pseudo-element {property: value}


The :first-line Pseudo-element

The "first-line" pseudo-element is used to add special styles to the first line of the text in a selector:

p {font-size: 12pt}
p:first-line {color: #0000FF; font-variant: small-caps}

Some text that ends up on two or more lines

The output could be something like this:

Some text that ends
up on two or more lines

In the example above the browser displays the first line formatted according to the "first-line" pseudo element. Where the browser breaks the line depends on the size of the browser window.

Note: The "first-line" pseudo-element can only be used with block-level elements.

Note: The following properties apply to the "first-line" pseudo-element:

  • font properties
  • color properties
  • background properties
  • word-spacing
  • letter-spacing
  • text-decoration
  • vertical-align
  • text-transform
  • line-height
  • clear

The :first-letter Pseudo-element

The "first-letter" pseudo-element is used to add special style to the first letter of the text in a selector:

p {font-size: 12pt}
p:first-letter {font-size: 200%; float: left}

The first words of an article.

The output could be something like this:

___
| he first
| words of an
article.

Note: The "first-letter" pseudo-element can only be used with block-level elements.

Note: The following properties apply to the "first-letter" pseudo- element:

  • font properties
  • color properties
  • background properties
  • margin properties
  • padding properties
  • border properties
  • text-decoration
  • vertical-align (only if 'float' is 'none')
  • text-transform
  • line-height
  • float
  • clear

Pseudo-elements and CSS Classes

Pseudo-elements can be combined with CSS classes:

p.article:first-letter {color: #FF0000}

A paragraph in an article

The example above will make the first letter of all paragraphs with class="article" red.


Multiple Pseudo-elements

Several pseudo-elements can be combined:

p {font-size: 12pt}
p:first-letter {color: #FF0000; font-size: 200%}
p:first-line {color: #0000FF}

The first words of an article

The output could be something like this:

___
| he first
| words of an
article.

In the example above the first letter of the paragraph will be red with a font size of 24pt. The rest of the first line would be blue while the rest of the paragraph would be the default color.


CSS2 - The :before Pseudo-element

The ":before" pseudo-element can be used to insert some content before an element.

The style below will play a sound before each occurrence of a header one element.

h1:before
{
content: url(beep.wav)
}


CSS2 - The :after Pseudo-element

The ":after" pseudo-element can be used to insert some content after an element.

The style below will play a sound after each occurrence of a header one element.

h1:after
{
content: url(beep.wav)
}


Pseudo-elements

Browser support: IE: Internet Explorer, F: Firefox, N: Netscape.

W3C: The number in the "W3C" column indicates in which CSS recommendation the property is defined (CSS1 or CSS2).

Pseudo-element

Purpose

IE

F

N

W3C

:first-letter

Adds special style to the first letter of a text

5

1

8

1

:first-line

Adds special style to the first line of a text

5

1

8

1

:before

Inserts some content before an element

1.5

8

2

:after

Inserts some content after an element

1.5

8

2


Media Types allow you to specify how documents will be presented in different media. The document can be displayed differently on the screen, on the paper, with an aural browser, etc.


Media Types

Some CSS properties are only designed for a certain media. For example the "voice-family" property is designed for aural user agents. Some other properties can be used for different media types. For example, the "font-size" property can be used for both screen and print media, but perhaps with different values. A document usually needs a larger font-size on a screen than on paper, and sans-serif fonts are easier to read on the screen, while serif fonts are easier to read on paper.


The @media Rule

The @media rule allows different style rules for different media in the same style sheet.

The style in the example below tells the browser to display a 14 pixels Verdana font on the screen. But if the page is printed, it will be in a 10 pixels Times font. Notice that the font-weight is set to bold, both on screen and on paper:

....

See it yourself ! If you are using Mozilla/Firefox or IE 5+ and print this page, you will see that the paragraph under "Media Types" will be displayed in another font, and have a smaller font size than the rest of the text.


Different Media Types

Note: The media type names are not case-sensitive.

Media Type

Description

all

Used for all media type devices

aural

Used for speech and sound synthesizers

braille

Used for braille tactile feedback devices

embossed

Used for paged braille printers

handheld

Used for small or handheld devices

print

Used for printers

projection

Used for projected presentations, like slides

screen

Used for computer screens

tty

Used for media using a fixed-pitch character grid, like teletypes and terminals

tv

Used for television-type devices


CSS Summary

This tutorial has taught you how to create style sheets to control the style and layout of multiple web sites at once.

You have learned how to use CSS to add backgrounds, format text, add and format borders, and specify padding and margins of elements.

You have also learned how to position an element, control the visibility and size of an element, set the shape of an element, place an element behind another, and to add special effects to some selectors, like links.

For more information on CSS, please take a look at our CSS examples and our CSS reference.


Now You Know CSS, What's Next?

The next step is to learn XHTML and JavaScript.

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