高度(height) 的 CSS 屬性指定了元素內容區域的高度。content area 在元素的留白(padding)、邊框(border) 與 邊界(margin) 內。

min-height (en-US)max-height (en-US) 的特性比 height 更重要。

Applies toall elements but non-replaced inline elements, table columns, and column groups
PercentagesThe percentage is calculated with respect to the height of the generated box's containing block. If the height of the containing block is not specified explicitly (i.e., it depends on content height), and this element is not absolutely positioned, the value computes to auto. A percentage height on the root element is relative to the initial containing block.
Computed value (en-US)a percentage or auto or the absolute length
Animation typea length, percentage or calc();


/* Keyword value */
height: auto;

/* <length> values */
height: 120px;
height: 10em;

/* <percentage> value */
height: 75%;

/* Global values */
height: inherit;
height: initial;
height: unset;

查看 <length> (en-US) 可用的單位。
<percentage> (en-US) 相對於元素的塊狀高度。如果沒有指定塊狀元素的高度,預設值為 auto。用在 root 元素 (e.g. <html>) 上是相對於初始塊狀元素(即顯示器的尺寸)。
border-box  Experimental
If present, the preceding <length> (en-US) or <percentage> (en-US) is applied to the element's border box.
content-box  Experimental
<length> (en-US)<percentage> (en-US) 是應用於元素的 content box.
fill Experimental
Use the fill-available inline size or fill-available block size, as appropriate to the writing mode.
max-content  Experimental
The intrinsic preferred height.
min-content  Experimental
The intrinsic minimum height.
available  Experimental
The containing block height minus vertical margin, border and padding.
fit-content  Experimental
The larger of:
  • the intrinsic minimum height
  • the smaller of the intrinsic preferred height and the available height




<div id="red">
  <span>I'm 50 pixels tall.</span>
<div id="green">
  <span>I'm 25 pixels tall.</span>
<div id="parent">
  <div id="child">
    <span>I'm half the height of my parent.</span>


div {
  width: 250px;
  margin-bottom: 5px;
  border: 3px solid #999999;

#red {
  height: 50px;

#green {
  height: 25px;

#parent {
  height: 100px;

#child {
  height: 50%;
  width: 75%;


Specification Status Comment
CSS Box Model
The definition of 'height' in that specification.
Candidate Recommendation Added the max-content, min-content, available, fit-content, border-box, content-box keywords.
CSS Transitions
The definition of 'height' in that specification.
Working Draft Lists height as animatable.
CSS Level 2 (Revision 1)
The definition of 'height' in that specification.
Recommendation Adds support for the <length> (en-US) values and precises on which element it applies to.
CSS Level 1
The definition of 'height' in that specification.
Recommendation Initial definition
CSS Box Sizing Module Level 3
The definition of 'width' in that specification.
Working Draft Adds new sizing keywords for width and height.


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See also