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padding-top - CSS（层叠样式表）编辑

CSS属性 padding-top 是指一个元素在内边距区域（padding area）中上方的高度。内边距（padding）是指一个元素的内容和边框之间的区域。和外边距（margin）不同，内边距（padding）是不允许有负值的。内边距（padding）可以用四个值声明一个元素的四个方向的内边距（paddings），这是一种CSS缩写属性。

The effect of the CSS padding-top property on the element box

/* <length> values */
padding-top: 0.5em;
padding-top: 0;
padding-top: 2cm;

/* <percentage> value */
padding-top: 10%;

/* Global values */
padding-top: inherit;
padding-top: initial;
padding-top: unset;

初始值	`0`
适用元素	all elements, except `table-row-group`, `table-header-group`, `table-footer-group`, `table-row`, `table-column-group` and `table-column`. It also applies to `::first-letter`.
是否是继承属性	否
Percentages	refer to the width of the containing block
适用媒体	visual
计算值	the percentage as specified or the absolute length
Animation type	a length
正规顺序	the unique non-ambiguous order defined by the formal grammar

语法规则

取值

length: 当内边距（padding）大小是一个固定单位数值的时候，一定不能为负数。
percentage: 当内边距（padding）是一个百分比的时候，百分比是和包含块（containing block）的宽度有关的，同样一定不能为负数。

正式语法

<length> | <percentage>

实例

.content { padding-top: 5%; }
.sidebox { padding-top: 10px; }

详细说明

Specification	Status	Comment
CSS Basic Box Model padding-top	Working Draft	No change from CSS Level 2 (Revision 1) padding-top.
CSS Transitions padding-top	Working Draft	Defines `padding-top` as animatable.
CSS Level 2 (Revision 1) padding-top	Recommendation	No change from CSS Level 1 padding-top.
CSS Level 1 padding-top	Recommendation	Initial definition.

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

Desktop
Mobile

Feature	Chrome	Edge	Firefox (Gecko)	Internet Explorer	Opera	Safari (WebKit)
Basic support	1.0	(Yes)	1.0 (1.0)	4.0	3.5	1.0 (85)

Feature	Android	Edge	Firefox Mobile (Gecko)	IE Phone	Opera Mobile	Safari Mobile
Basic support	?	(Yes)	?	?	?	?

更多浏览

CSS Box Model
The padding shorthand property can be used to set paddings on all four sides of an element with a single declaration: padding-top, padding-right, padding-bottom, and padding-left.