背景 | background
背景
CSS background
速记属性允许您一次调整所有可用的背景样式选项,包括彩色图像,原点和大小,重复方法以及其他功能。background
可用于对一个或多个设置值:background-clip
,background-color
,background-image
,background-origin
,background-position
,background-repeat
,background-size
,和background-attachment
。
/* Using a <background-color> */
background: green;
/* Using a <bg-image> and <repeat-style> */
background: url("test.jpg") repeat-y;
/* Using a <box> and <background-color> */
background: border-box red;
/* A single image, centered and scaled */
background: no-repeat center/80% url("../img/image.png"
background
CSS简写属性明确分配给定的值,并设置缺少的属性为初始值。
初始值 | 作为简写的每个属性:background-image:none background-position:0%0%background-size:auto auto background-repeat:repeat background-origin:padding-box background-clip:border-box background-attachment :滚动背景颜色:透明 |
---|---|
适用于 | 所有元素。它也适用于:: first-letter和:: first-line。 |
遗传 | 没有 |
百分比 | 作为简写的每个属性:background-position:指背景定位区域的大小减去背景图像的大小; 大小是指水平偏移的宽度和垂直偏移的高度background-size:相对于背景定位区域 |
媒体 | 视觉 |
计算值 | 作为速记的每个属性:background-image:如指定的那样,但url值被设置为absolute-background-position:一个列表,每个项目由两个关键字组成,这两个关键字分别代表原点和来自该原点的两个偏移量,每个偏移量都以绝对值长度(如果给定<length>),否则为百分比background-size:按照指定,但相对长度转换为绝对长度background-repeat:列表,每个项目由两个关键字组成,每个维度一个background-origin:如指定background-clip:指定background-attachment:指定background-color:计算颜色 |
动画类型 | 作为简写的每个属性:background-color:一种颜色background-image:离散background-clip:离散background-position:长度,百分比或calc的简单列表的可重复列表background-size:简单列表的可重复列表长度,百分比或计算背景重复:离散背景附件:离散 |
规范的顺序 | 出现在价值形式语法中的顺序 |
background-image
:none
Applies to all elements. It also applies to [`::first-letter`](::first-letter) and [`::first-line`](::first-line). [Inherited](inheritance) no Percentages as each of the properties of the shorthand:
background-position
:指背景定位区域的大小减去背景图像的大小; 大小是指水平偏移的宽度和垂直偏移的高度
Media visual [Computed value](computed_value) as each of the properties of the shorthand:
background-image
:如指定的那样,但是具有url
绝对值
Animation type as each of the properties of the shorthand:
background-color
:一种颜色
Canonical order order of appearance in the formal grammar of the values
句法
background
属性被指定为一个或多个背景层,用逗号分隔。
每个图层的语法如下所示:
- 每个图层可能包含零个或一个以下任何值:
值
<attachment>参见background-attachment<box>参见background-clip和background-origin<background-color>参见background-color<bg-image>参见background-image<position>参见background-position<repeat-style>参见background-repeat<bg-size>参见background-size。
形式语法
[ <bg-layer> , ]* <final-bg-layer>where <bg-layer> = <bg-image> || <position> [ / <bg-size> ]? || <repeat-style> || <attachment> || <box>{1,2}<final-bg-layer> = <bg-image> || <position> [ / <bg-size> ]? || <repeat-style> || <attachment> || <box> || <box> || <'background-color'>where <bg-image> = none | <image><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>? ]]<bg-size> = [ <length-percentage> | auto ]{1,2} | cover | contain<repeat-style> = repeat-x | repeat-y | [ repeat | space | round | no-repeat ]{1,2}<attachment> = scroll | fixed | local<box> = border-box | padding-box | content-boxwhere <image> = <url> | <image()> | <image-set()> | <element()> | <cross-fade()> | <gradient><length-percentage> = <length> | <percentage>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( [ [ <percentage>{3} | <number>{3} ] [ / <alpha-value> ]? ] | [ [ <percentage>#{3} | <number>#{3} ] , <alpha-value>? ] )<rgba()> = rgba( [ [ <percentage>{3} | <number>{3} ] [ / <alpha-value> ]? ] | [ [ <percentage>#{3} | <number>#{3} ] , <alpha-value>? ] )<hsl()> = hsl( [ <hue> <percentage> <percentage> [ / <alpha-value> ]? ] | [ <hue>, <percentage>, <percentage>, <alpha-value>? ] )<hsla()> = hsla( [ <hue> <percentage> <percentage> [ / <alpha-value> ]? ] | [ <hue>, <percentage>, <percentage>, <alpha-value>? ] )<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}where <alpha-value> = <number> | <percentage><hue> = <number> | <angle><color-stop> = <color> <length-percentage>?
示例
HTML
<p class="topbanner">
Starry sky<br/>
Twinkle twinkle<br/>
Starry sky
</p>
<p class="warning">Here is a paragraph<p>
CSS
.warning {
background: pink;
}
.topbanner {
background: url("https://mdn.mozillademos.org/files/11983/starsolid.gif") #99f repeat-y fixed;
}
结果
规范
规范 | 状态 | 评论 |
---|---|---|
CSS背景和边框模块级别3在该规范中定义“背景”。 | 候选推荐 | 速记属性已扩展为支持多个背景和新的背景大小,背景源和背景剪辑属性。 |
CSS级别2(修订1)该规范中“背景”的定义。 | 建议 | 没有重大变化 |
CSS级别1该规范中“背景”的定义。 | 建议 | 初始定义 |
浏览器兼容性
特征 | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
基本支持 | 1.0 | 12 | 1.0 | 4 | 3.5 | 1.0 |
多个背景 | 1.0 | 12 | 3.6 | 9 | 10.5 | 1.3 |
SVG图像作为背景 | 31.0 | 12 | 9.0 | 9.0 | 21.0 | 5.1 |
背景尺寸longhand的值 | 21.0 | 12 | 9.0 | 9.0 | 21.0 | 5.1 |
背景来源的longhand值 | 21.0 | 12 | 22.0 | 9.0 | 21.0 | 5.1 |
背景剪辑longhand的值 | 21.0 | 12 | 22.0 | 9.0 | 21.0 | 5.1 |
特征 | Android | Chrome for Android | Edge mbile | Firefox for Android | IE mobile | Opera Android | iOS Safari |
---|---|---|---|---|---|---|---|
基本支持 | 2.1 | ? | (是) | 1.0 | 10.0 | 5.0 | 3.2 |
多个背景 | 2.1 | ? | (是) | 1.0 | 10.0 | ? | 3.2 |
SVG图像作为背景 | 3.0 | ? | (是) | 4.0 | 10.0 | (是) | 4.2 |
背景尺寸longhand的值 | 3.0 | ? | (是) | 18.0 | 10.0 | (是) | 4.0 |
背景来源的longhand值 | 3.0 | ? | (是) | 22.0 | 10.0 | 没有 | 4.0 |
背景剪辑longhand的值 | 3.0 | ? | (是) | 22.0 | 10.0 | 没有 | 4.0 |