我們的志工尚未將此文章翻譯為 正體中文 (繁體) 版本。加入我們,幫忙翻譯!
Summary
The CSS background-image
property sets one or several background images for an element. The images are drawn on stacking context layers on top of each other. The first layer specified is drawn as if it is closest to the user.
The borders of the element are then drawn on top of them, and the background-color
is drawn beneath them. How the images are drawn relative to the box and its borders is defined by the background-clip
and background-origin
CSS properties.
If a specified image cannot be drawn (for example, when the file denoted by the specified URI cannot be loaded), browsers handle it as they would a none
value.
background-color
. If the images cannot be loaded—for instance, when the network is down—the background color will be used as a fallback.Initial value | none |
---|---|
Applies to | all elements. It also applies to ::first-letter and ::first-line . |
Inherited | no |
Media | visual |
Computed value | as specified, but with URIs made absolute |
Animation type | discrete |
Canonical order | the unique non-ambiguous order defined by the formal grammar |
Syntax
background-image: none; background-image: url("https://www.example.com/bck.png"); background-image: inherit;
Values
none
- Is a keyword denoting the absence of images.
<image>
- Is an
<image>
denoting the image to display. There can be several of them, separated by commas, as multiple backgrounds are supported.
Formal syntax
<bg-image>#where
<bg-image> = none | <image>
where
<image> = <url> | <image()> | <image-set()> | <element()> | <cross-fade()> | <gradient>
where
<image()> = image( [ [ <image> | <string> ]? , <color>? ]! )
<image-set()> = image-set( <image-set-option># )
<element()> = element( <id-selector> )
<cross-fade()> = cross-fade( <cf-mixing-image> , <cf-final-image>? )
<gradient> = <linear-gradient()> | <repeating-linear-gradient()> | <radial-gradient()> | <repeating-radial-gradient()>where
<color> = <rgb()> | <rgba()> | <hsl()> | <hsla()> | <hex-color> | <named-color> | currentcolor | <deprecated-system-color>
<image-set-option> = [ <image> | <string> ] <resolution>
<cf-mixing-image> = <percentage>? && <image>
<cf-final-image> = <image> | <color>
<linear-gradient()> = linear-gradient( [ <angle> | to <side-or-corner> ]? , <color-stop-list> )
<repeating-linear-gradient()> = repeating-linear-gradient( [ <angle> | to <side-or-corner> ]? , <color-stop-list> )
<radial-gradient()> = radial-gradient( [ <ending-shape> || <size> ]? [ at <position> ]? , <color-stop-list> )
<repeating-radial-gradient()> = repeating-radial-gradient( [ <ending-shape> || <size> ]? [ at <position> ]? , <color-stop-list> )where
<rgb()> = rgb( <rgb-component>#{3} )
<rgba()> = rgba( <rgb-component>#{3} , <alpha-value> )
<hsl()> = hsl( <hue>, <percentage>, <percentage> )
<hsla()> = hsla( <hue>, <percentage>, <percentage>, <alpha-value> )
<named-color> = <ident>
<deprecated-system-color> = ActiveBorder | ActiveCaption | AppWorkspace | Background | ButtonFace | ButtonHighlight | ButtonShadow | ButtonText | CaptionText | GrayText | Highlight | HighlightText | InactiveBorder | InactiveCaption | InactiveCaptionText | InfoBackground | InfoText | Menu | MenuText | Scrollbar | ThreeDDarkShadow | ThreeDFace | ThreeDHighlight | ThreeDLightShadow | ThreeDShadow | Window | WindowFrame | WindowText
<side-or-corner> = [ left | right ] || [ top | bottom ]
<color-stop-list> = <color-stop>{2,}
<ending-shape> = circle | ellipse
<size> = closest-side | farthest-side | closest-corner | farthest-corner | <length> | <length-percentage>{2}
<position> = [[ left | center | right | top | bottom | <length-percentage> ] | [ left | center | right | <length-percentage> ] [ top | center | bottom | <length-percentage> ] | [ center | [ left | right ] <length-percentage>? ] && [ center | [ top | bottom ] <length-percentage>? ]]where
<rgb-component> = <integer> | <percentage>
<alpha-value> = <number>
<hue> = <number>
<color-stop> = <color> <length-percentage>?
<length-percentage> = <length> | <percentage>
Examples
Note that the star image is partially transparent and is layered over the cat image.
HTML
<div> <p class="catsandstars"> This paragraph is full of cats<br />and stars. </p> <p>This paragraph is not.</p> <p class="catsandstars"> Here are more cats for you.<br />Look at them! </p> <p>And no more.</p> </div>
CSS
pre, p { font-size: 1.5em; color: #FE7F88; background-color: transparent; } div { background-image: url("https://mdn.mozillademos.org/files/6457/mdn_logo_only_color.png"); } p { background-image: none; } .catsandstars { background-image: url("https://mdn.mozillademos.org/files/11991/startransparent.gif"), url("https://mdn.mozillademos.org/files/7693/catfront.png"); background-color: transparent; }
Result
Specifications
Specification | Status | Comment |
---|---|---|
CSS Backgrounds and Borders Module Level 3 The definition of 'background-image' in that specification. |
Candidate Recommendation | From CSS2 Revision 1, the property has been extended to support multiple backgrounds and any <image> CSS data type. |
CSS Level 2 (Revision 1) The definition of 'background-image' in that specification. |
Recommendation | From CSS1, the way images with and without intrinsic dimensions are handled is now described. |
CSS Level 1 The definition of 'background-image' in that specification. |
Recommendation | Initial definition |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | 1.0 | 1.0 (1.7 or earlier)[1] | 4.0 | 3.5 | 1.0 |
Multiple backgrounds | 1.0 | 3.6 (1.9.2) | 9.0 | (Yes) | 1.3 |
Gradients | 1.0-webkit | 3.6 (1.9.2)-moz | 10 | 11-o | 4.0-webkit |
SVG images | 8.0 | 4.0 (2.0) | 9.0 | 9.5 | 5.0 [2] |
element |
? | (Yes)-moz | No support | No support | No support |
image-rect |
No support | (Yes)-moz | No support | No support | No support |
Any <image> value. |
? | No support | ? | ? | ? |
Feature | Safari Mobile | Opera Mini | Opera Mobile | Android |
---|---|---|---|---|
Basic support | (Yes) | (Yes) | (Yes) | (Yes) |
Multiple backgrounds | (Yes) | (Yes) | (Yes) | (Yes) |
Gradients | (Yes) -webkit [3] |
? | ? | (Yes) -webkit [4] |
SVG images | (Yes) [2] | (Yes) | (Yes) | No support |
element |
(Yes)-moz | ? | ? | ? |
image-rect |
(Yes)-moz | No support | No support | No support |
Any <image> value |
No support | ? | ? | ? |
[1] If the browser.display.use_document_colors
user preference in about:config
is set to false
, background images will not de displayed.
[2] Support of SVG in CSS background is incomplete in the current version of iOS Safari (5.0). The same for Safari prior 5.0.
[3] Old webkit syntax for iOS 4.2 and older
[4] Old webkit syntax
See also
- CSS Image Sprites
<img>
- Image-related articles:
<image>
,linear-gradient()
,radial-gradient()
,repeating-linear-gradient()
,repeating-radial-gradient()
,element()
.