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• 句法
• 形式定义
• 形式句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

background-position-y CSS property sets the initial vertical position for each background image. The position is relative to the position layer set by background-origin .

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

The value of this property is overridden by any declaration of the background or background-position shorthand properties applied to the element after it.

句法

/* Keyword values */
background-position-y: top;
background-position-y: center;
background-position-y: bottom;
/* <percentage> values */
background-position-y: 25%;
/* <length> values */
background-position-y: 0px;
background-position-y: 1cm;
background-position-y: 8em;
/* Side-relative values */
background-position-y: bottom 3px;
background-position-y: bottom 10%;
/* Multiple values */
background-position-y: 0px, center;
/* Global values */
background-position-y: inherit;
background-position-y: initial;
background-position-y: unset;
					

background-position-y property is specified as one or more values, separated by commas.

值

top

Aligns the top edge of the background image with the top edge of the background position layer.

center

Aligns the vertical center of the background image with the vertical center of the background position layer.

bottom

Aligns the bottom edge of the background image with the bottom edge of the background position layer.

<length>

The offset of the given background image's horizontal edge from the corresponding background position layer's top horizontal edge. (Some browsers allow assigning the bottom edge for offset).

<percentage>

The offset of the given background image's vertical position relative to the container. A value of 0% means that the top edge of the background image is aligned with the top edge of the container, and a value of 100% means that the bottom edge of the background image is aligned with the bottom edge of the container, thus a value of 50% vertically centers the background image.

形式定义

初始值	top
适用于	所有元素
继承	no
百分比	refer to height of background positioning area minus height of background image
计算值	A list, each item consisting of: an offset given as a combination of an absolute length and a percentage, plus an origin keyword
动画类型	discrete

形式句法

[ center | [ [ top | bottom | y-start | y-end ]? <length-percentage>? ]! ]#
where 
<length-percentage> = <length> | <percentage>
					

范例

基本范例

The following example shows a simple background image implementation, with background-position-x and background-position-y used to define the image's horizontal and vertical positions separately.

HTML

<div></div>
					

CSS

div {
  width: 300px;
  height: 300px;
  background-color: skyblue;
  background-image: url(https://media.prod.mdn.mozit.cloud/attachments/2020/07/29/17350/3b4892b7e820122ac6dd7678891d4507/firefox.png);
  background-repeat: no-repeat;
  background-position-x: center;
  background-position-y: bottom 10px;
}
					

结果

规范

规范	状态	注释
CSS Backgrounds and Borders Module Level 4 The definition of 'background-position-y' in that specification.	编者草案	Initial specification of longhand sub-properties of background-position to match longstanding implementations.

浏览器兼容性

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

更新 GitHub 上的兼容性数据

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
background-position-y	Chrome 完整支持 1	Edge 完整支持 12	Firefox 完整支持 49	IE 完整支持 6	Opera 完整支持 15	Safari 完整支持 1	WebView Android 完整支持 ≤37	Chrome Android 完整支持 18	Firefox Android 完整支持 49	Opera Android 完整支持 14	Safari iOS 完整支持 1	Samsung Internet Android 完整支持 1.0
Two-value syntax (support for offsets from any edge)	Chrome 不支持 No	Edge 不支持 12 — 79	Firefox 完整支持 49	IE 完整支持 9	Opera 不支持 No	Safari 不支持 No	WebView Android 不支持 No	Chrome Android 不支持 No	Firefox Android 完整支持 49	Opera Android 不支持 No	Safari iOS 不支持 No	Samsung Internet Android 不支持 No

图例

完整支持

完整支持

不支持

不支持

另请参阅

• background-position
• background-position-x
• background-position-inline
• background-position-block
• Using multiple backgrounds

元数据

• 最后修改： Aug 2, 2020

相关话题

1. CSS
2. CSS 参考
3. CSS Backgrounds and Borders
4. 指南

   1. Resizing background images with background-size
   2. Using multiple backgrounds
5. 特性

   1. background
   2. background-attachment
   3. background-clip
   4. background-color
   5. background-image
   6. background-origin
   7. background-position
   8. background-position-x
   9. background-position-y
   10. background-repeat
   11. background-size
   12. border
   13. border-bottom
   14. border-bottom-color
   15. border-bottom-left-radius
   16. border-bottom-right-radius
   17. border-bottom-style
   18. border-bottom-width
   19. border-color
   20. border-image
   21. border-image-outset
   22. border-image-repeat
   23. border-image-slice
   24. border-image-source
   25. border-image-width
   26. border-left
   27. border-left-color
   28. border-left-style
   29. border-left-width
   30. border-radius
   31. border-right
   32. border-right-color
   33. border-right-style
   34. border-right-width
   35. border-style
   36. border-top
   37. border-top-color
   38. border-top-left-radius
   39. border-top-right-radius
   40. border-top-style
   41. border-top-width
   42. border-width
   43. box-shadow