Background size css javascript

CSS background Property

Set different background properties in one declaration:

Definition and Usage

The background property is a shorthand property for:

It does not matter if one of the values above are missing, e.g. background:#ff0000 url(smiley.gif); is allowed.

Default value:	see individual properties
Inherited:	no
Animatable:	yes, see individual properties. Read about animatable Try it
Version:	CSS1 + new properties in CSS3
JavaScript syntax:	object.style.background=»red url(smiley.gif) top left no-repeat» Try it

Browser Support

The numbers in the table specify the first browser version that fully supports the property.

Note: See individual browser support for each value below.

CSS Syntax

background: bg-color bg-image position/bg-size bg-repeat bg-origin bg-clip bg-attachment initial|inherit;

Note: If one of the properties in the shorthand declaration is the bg-size property, you must use a / (slash) to separate it from the bg-position property, e.g. background:url(smiley.gif) 10px 20px/50px 50px; will result in a background image, positioned 10 pixels from the left, 20 pixels from the top, and the size of the image will be 50 pixels wide and 50 pixels high.

Note: If using multiple background-image sources but also want a background-color, the background-color parameter needs to be last in the list.

Property Values

Value	Description	CSS	Demo
background-color	Specifies the background color to be used	1	Demo ❯
background-image	Specifies ONE or MORE background images to be used	1	Demo ❯
background-position	Specifies the position of the background images	1	Demo ❯
background-size	Specifies the size of the background images	3	Demo ❯
background-repeat	Specifies how to repeat the background images	1	Demo ❯
background-origin	Specifies the positioning area of the background images	3	Demo ❯
background-clip	Specifies the painting area of the background images	3	Demo ❯
background-attachment	Specifies whether the background images are fixed or scrolls with the rest of the page	1
initial	Sets this property to its default value. Read about initial	3
inherit	Inherits this property from its parent element. Read about inherit	2

Источник

background-size

The background-size CSS property sets the size of the element’s background image. The image can be left to its natural size, stretched, or constrained to fit the available space.

Try it

Spaces not covered by a background image are filled with the background-color property, and the background color will be visible behind background images that have transparency/translucency.

Syntax

/* Keyword values */ background-size: cover; background-size: contain; /* One-value syntax */ /* the width of the image (height becomes 'auto') */ background-size: 50%; background-size: 3.2em; background-size: 12px; background-size: auto; /* Two-value syntax */ /* first value: width of the image, second value: height */ background-size: 50% auto; background-size: 3em 25%; background-size: auto 6px; background-size: auto auto; /* Multiple backgrounds */ background-size: auto, auto; /* Not to be confused with `auto auto` */ background-size: 50%, 25%, 25%; background-size: 6px, auto, contain; /* Global values */ background-size: inherit; background-size: initial; background-size: revert; background-size: revert-layer; background-size: unset; 

The background-size property is specified in one of the following ways:

• Using the keyword values contain or cover .
• Using a width value only, in which case the height defaults to auto .
• Using both a width and a height value, in which case the first sets the width and the second sets the height. Each value can be a , a , or auto .

To specify the size of multiple background images, separate the value for each one with a comma.

Values

Scales the image as large as possible within its container without cropping or stretching the image. If the container is larger than the image, this will result in image tiling, unless the background-repeat property is set to no-repeat .

Scales the image (while preserving its ratio) to the smallest possible size to fill the container (that is: both its height and width completely cover the container), leaving no empty space. If the proportions of the background differ from the element, the image is cropped either vertically or horizontally.

Scales the background image in the corresponding direction such that its intrinsic proportions are maintained.

Stretches the image in the corresponding dimension to the specified length. Negative values are not allowed.

Stretches the image in the corresponding dimension to the specified percentage of the background positioning area. The background positioning area is determined by the value of background-origin (by default, the padding box). However, if the background’s background-attachment value is fixed , the positioning area is instead the entire viewport. Negative values are not allowed.

Intrinsic dimensions and proportions

The computation of values depends on the image’s intrinsic dimensions (width and height) and intrinsic proportions (width-to-height ratio). These attributes are as follows:

• A bitmap image (such as JPG) always has intrinsic dimensions and proportions.
• A vector image (such as SVG) does not necessarily have intrinsic dimensions. If it has both horizontal and vertical intrinsic dimensions, it also has intrinsic proportions. If it has no dimensions or only one dimension, it may or may not have proportions.
• CSS s have no intrinsic dimensions or intrinsic proportions.
• Background images created with the element() function use the intrinsic dimensions and proportions of the generating element.

Note: In Gecko, background images created using the element() function are currently treated as images with the dimensions of the element, or of the background positioning area if the element is SVG, with the corresponding intrinsic proportion. This is non-standard behavior.

Based on the intrinsic dimensions and proportions, the rendered size of the background image is computed as follows:

• If both components of background-size are specified and are not auto : The background image is rendered at the specified size.
• If the background-size is contain or cover : While preserving its intrinsic proportions, the image is rendered at the largest size contained within, or covering, the background positioning area. If the image has no intrinsic proportions, then it’s rendered at the size of the background positioning area.
• If the background-size is auto or auto auto :
  • If the image has both horizontal and vertical intrinsic dimensions, it’s rendered at that size.
  • If the image has no intrinsic dimensions and has no intrinsic proportions, it’s rendered at the size of the background positioning area.
  • If the image has no intrinsic dimensions but has intrinsic proportions, it’s rendered as if contain had been specified instead.
  • If the image has only one intrinsic dimension and has intrinsic proportions, it’s rendered at the size corresponding to that one dimension. The other dimension is computed using the specified dimension and the intrinsic proportions.
  • If the image has only one intrinsic dimension but has no intrinsic proportions, it’s rendered using the specified dimension and the other dimension of the background positioning area.

  Note: SVG images have a preserveAspectRatio attribute that defaults to the equivalent of contain ; an explicit background-size causes preserveAspectRatio to be ignored.

  • If the image has intrinsic proportions, it’s stretched to the specified dimension. The unspecified dimension is computed using the specified dimension and the intrinsic proportions.
  • If the image has no intrinsic proportions, it’s stretched to the specified dimension. The unspecified dimension is computed using the image’s corresponding intrinsic dimension, if there is one. If there is no such intrinsic dimension, it becomes the corresponding dimension of the background positioning area.

  Note: Background sizing for vector images that lack intrinsic dimensions or proportions is not yet fully implemented in all browsers. Be careful about relying on the behavior described above, and test in multiple browsers to be sure the results are acceptable.

  Formal definition

  Initial value	auto auto
  Applies to	all elements. It also applies to ::first-letter and ::first-line .
  Inherited	no
  Percentages	relative to the background positioning area
  Computed value	as specified, but with relative lengths converted into absolute lengths
  Animation type	a repeatable list of

  Formal syntax

  Examples

  Tiling a large image

  Let’s consider a large image, a 2982×2808 Firefox logo image. We want to tile four copies of this image into a 300×300-pixel element. To do this, we can use a fixed background-size value of 150 pixels.

  HTML

  div class="tiledBackground">div> 

  CSS

  .tiledBackground  background-image: url(https://www.mozilla.org/media/img/logos/firefox/logo-quantum.9c5e96634f92.png); background-size: 150px; width: 300px; height: 300px; border: 2px solid; color: pink; > 

  Result

  Specifications

  Browser compatibility

  BCD tables only load in the browser

  See also

  Found a content problem with this page?

  This page was last modified on Jul 18, 2023 by MDN contributors.

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  Источник

  Style backgroundSize Property

  The backgroundSize property sets or returns the size of the background images.

  See Also:

  Syntax

  Return the backgroundSize property:

  Set the backgroundSize property:

  Property Values

  Value	Description
  auto	Default value. The background-image contains its width and height
  length	Sets the width and height of the background image. The first value sets the width, the second value sets the height. If only one value is given, the second is set to «auto»
  percentage	Sets the width and height of the background image in percent of the parent element. The first value sets the width, the second value sets the height. If only one value is given, the second is set to «auto»
  cover	Scale the background image to be as large as possible so that the background area is completely covered by the background image. Some parts of the background image may not be in view within the background positioning area
  contain	Scale the image to the largest size such that both its width and its height can fit inside the content area
  initial	Sets this property to its default value. Read about initial
  inherit	Inherits this property from its parent element. Read about inherit

  Technical Details

  Default Value:	auto
  Return Value:	A String, representing the background-size property of an element
  CSS Version	CSS3

  Browser Support

  backgroundSize is a CSS3 (1999) feature.

  It is fully supported in all browsers:

  Chrome	Edge	Firefox	Safari	Opera	IE
  Yes	Yes	Yes	Yes	Yes	11

  Источник