ackground-position-xCSS 属性设置水平方向的位置，与每个背景图片等位置层设置属性 background-origin相关。更多信息请查看background-position属性，这个用的比较普遍。
/* Keyword values */ background-position-x: left; background-position-x: center; background-position-x: right; /* <percentage> values */ background-position-x: 25%; /* <length> values */ background-position-x: 0px; background-position-x: 1cm; background-position-x: 8em; /* side-relative values */ background-position-x: right 3px; background-position-x: left 25%; /* Multiple values */ background-position-x: 0px, center; /* Global values */ background-position-x: inherit; background-position-x: initial; background-position-x: unset;
注意：这个属性的值会被后面声明的属性覆盖掉，如background和background-position等简写的属性。
|
初始值 |
left |
|---|---|
|
适用元素 |
all elements |
|
是否是继承属性 |
no |
|
Percentages |
refer to width of background positioning area minus height of background image |
|
适用媒体 |
visual |
|
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 |
|
Animation type |
discrete |
|
正规顺序 |
the unique non-ambiguous order defined by the formal grammar |
语法
值
left在位置层上相对于左边的位置。center在位置层上相对于中间点的位置。right在位置层上相对于右边的位置。<length><length>值是定义相对于位置层边缘的距离，边缘默认为左边。<percentage><percentage>值是定义相对于位置层边缘的距离百分比，边缘默认为左边。
正式语法
[ center | [ left | right | x-start | x-end ]? <length-percentage>? ]#where <length-percentage> = <length> | <percentage>
规范
|
Specification |
Status |
Comment |
|---|---|---|
|
CSS Backgrounds and Borders Module Level 4The definition of 'background-position-x' in that specification. |
Editor's Draft |
Initial specification of longhand sub properties of background-position to match longstanding implementations. |
浏览器兼容性
|
Feature |
Chrome |
Firefox |
Edge |
Internet Explorer |
Opera |
Safari |
|---|---|---|---|---|---|---|
|
Basic Support |
(Yes) |
49.0 |
12 |
6 |
(Yes) |
(Yes) |
|
Two-value syntax (support for offsets from any edge) |
(No) |
49.0 |
12 |
9.0 |
(No) |
(No) |
|
Feature |
Android |
Chrome for Android |
Edge mobile |
Firefox for Android |
IE mobile |
Opera Android |
iOS Safari |
|---|---|---|---|---|---|---|---|
|
Basic Support |
(Yes) |
(Yes) |
(Yes) |
49.0 |
? |
? |
? |
|
Two-value syntax (support for offsets from any edge) |
(No) |
(No) |
(Yes) |
49.0 |
? |
(No) |
(No) |
另见
background-position
background-position-y
- 多重背景（Multiple backgrounds）
