The CSS reference

"background-position" - css property (v. css 1)

  • Indicates the starting position of a background image.
  • You can use a couple of % values or lengths to specify a position location
  • A specified position relates to the upper left corner of the box that surrounds the content of the element.
  • It is possible to combine a length and a % value to specify a position.
  • Alternatively you can use two keywords to specify a position location.
  • Initial value: 0% 0%
  • The property is not inherited
  • HTML usage: block-level and replaced elements
  • Note: You cannot combine % or length with a keyword.
  • Browsers that support the background-position - property :
    Internet Explorer Mozilla Firefox Opera Google Chrome Apple Safari

Possible property values:

Values Comments CSS
percentage If only one percentage or length value is given, it sets the horizontal position only, the vertical position will be 50%. 1
percentage percentage The first percentage is for the horizontal position and the last percentage is for the vertical position. 1
length The length value is for the horizontal position only, the vertical position will be 50%. Length are given in units - ref. unit table belove. 1
length length The first length is for the horizontal position and the last length is for the vertical position. Length are given in units - ref. unit table belove. 1
percentage length The percentage is for the horizontal position and the length is for the vertical position. Length are given in units - ref. unit table belove. 1
length percentage The length is for the horizontal position and the percentage is for the vertical position. Length are given in units - ref. unit table belove. 1
top left |
left top
The horizontal position will be at 0% and the vertical position will be at 0%. (this is the default) 1
top |
center top |
top center
The horizontal position will be at 50% and the vertical position will be at 0%. 1
top right |
right top
The horizontal position will be at 100% and the vertical position will be at 0%. 1
left |
left center |
center left
The horizontal position will be at 0% and the vertical position will be at 50%. 1
center |
center center
The horizontal position will be at 50% and the vertical position will be at 50%. 1
right |
right center |
center right
The horizontal position will be at 100% and the vertical position will be at 50%. 1
left bottom |
bottom left
The horizontal position will be at 0% and the vertical position will be at 100%. 1
bottom |
bottom center |
center bottom
The horizontal position will be at 50% and the vertical position will be at 100%. 1
bottom right |
right bottom
The horizontal position will be at 100% and the vertical position will be at 100%. 1
inherit Will inherit the position from parent specification. This property value is new with CSS 2. 2
Here are some possible property value examples:
Property Value Comment
50% If only one percentage or length value is given, it sets the horizontal position only, the vertical position will be 50%.
Example:
div.mylogo {
  background-image: url(logo.png);
  background-attachment: fixed;
  background-position: 50%;
} 
50% 50% Same result as above.
center Same result as above.
center center Same result as above.
0% The background image is placed at the left side of the box that surrounds the content of the element, the vertical position will still be 50%.
Example:
div.mylogo {
  background-image: url(logo.png);
  background-attachment: fixed;
  background-position: 0%;
} 
left Same result as above.
left center Same result as above.
center left Same result as above.
50% 0% The background image is placed at the top of the box that surrounds the content of the element, the horizontal position will be 50%.
top Same result as above.
top center Same result as above.
center top Same result as above.
50% 100% The background image is placed at the bottom of the box that surrounds the content of the element, the horizontal position will be 50%.
bottom Same result as above.
bottom center Same result as above.
center bottom Same result as above.
100% 0% The background image is placed at the top of the box that surrounds the content of the element, the horizontal position will be 100%.
top right Same result as above.
right top Same result as above.
10px 20px The background image is placed at 10px from the left side and 20px from the top of the box that surrounds the content of the element.
  • The format of a length value is an optional sign character ('+' or '-', with '+' being the default) immediately followed by a number immediately followed by a unit identifier.

Possible unit identifier:

unit identifier Comments CSS
em The relative unit 'em' is relative to the font size of the element itself. 1
ex The relative unit 'ex' is relative to the font size of the element itself. 1
px Pixels, relative to the viewing device 1
in inches -> 1 inch is equal to 2.54 centimeters. 1
cm centimeters. 1
mm millimeters. 1
pt points -> the points used by CSS2 are equal to 1/72th of an inch. 1
pc picas -> 1 pica is equal to 12 points. 1

Property "background-position" example:

<html>
<head>
<style type="text/css">
  body { background-image: url(images/Trophy.png);
         background-color: #cdcdcd;
	 background-repeat: no-repeat;
         background-position: 50% -50%;}
</style>
</head>
<body>
</body>
</html>

Javascript access:

// To SET values ([o] is the target object) 
[o].style.backgroundPosition="background-position value"
// To GET values you must first get the computed style object
// To get that object in IE or Opera:
var cStyle=[o].currentStyle;
// To get that object in Firefox, Chrome or Safari (w3c-type):
var cStyle=window.getComputedStyle([o],null);
// To GET the property values:
var value=cStyle.backgroundPosition;
// IE will return 'undefined'
// Opera will return value pairs in pixel.
// Firefox, Chrome and Safari will return value pairs in %. 
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