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
  • 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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