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What is CSS?


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 <link> tag. The <link> tag goes inside the head section.

<head>
<link rel="stylesheet" type="text/css"
href="mystyle.css">
</head>

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 with the <style> tag.

<head>
<style type="text/css">
body {background-color: red}
p {margin-left: 20px}
</style>
</head>

Inline Styles

An inline style should be used when a unique 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.


Inline Style Examples

using the style attribute of many tags

<p style="color: red; margin-left: 20px">
This is a red paragraph that is indented 20px.
</p>

This is a red paragraph that is indented 20px.

This is a div with a font-size of 24 px

A link that is not underlined.
This is a link to lastpage.htm
And more and more css examples

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 <head> 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 <head> tag, in an external style sheet, or in a browser (a default value).


CSS Properties

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(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%
xpos ypos
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

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
line-height Sets the distance between lines normal
number
length
%
4 1 4 1
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

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

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

CSS Outline Properties

An outline is a line that is drawn around elements, outside the border edge, to make the element "stand out".

The CSS outline properties sets the outlines around elements. You can specify the style, color, and width of the outline.

Note: Outlines do not take up space, and they do not have to be rectangular.

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
outline A shorthand property for setting all the outline properties in one declaration outline-color
outline-style
outline-width
- 1.5 - 2
outline-color Sets the color of the outline around an element color
invert
- 1.5 - 2
outline-style Sets the style of the outline around an element none
dotted
dashed
solid
double
groove
ridge
inset
outset
- 1.5 - 2
outline-width Sets the width of the outline around an element thin
medium
thick
length
- 1.5 - 2

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

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

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

CSS Table Properties

The CSS table properties allow you to set the layout of a table.

Browser support: IE: Internet Explorer, M: Mac IE only, 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-collapse Sets whether the table borders are collapsed into a single border or detached as in standard HTML collapse
separate
5 1 7 2
border-spacing Sets the distance that separates cell borders (only for the "separated borders" model) length length 5M 1 6 2
caption-side Sets the position of the table caption top
bottom
left
right
5M 1 6 2
empty-cells Sets whether or not to show empty cells in a table (only for the "separated borders" model)  show
hide
5M 1 6 2
table-layout Sets the algorithm used to display the table cells, rows, and columns auto
fixed
5 1 6 2

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

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

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

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 - 1.5 8 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 7 1 7 2
:lang Allows the author to specify a language to use in a specified element - 1 8 2

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