高度(height) 的 CSS 屬性指定了元素內容區域的高度。content area (en-US) 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。

預設值 (en-US)auto
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 實驗性質

If present, the preceding <length> (en-US) or <percentage> (en-US) is applied to the element's border box.

content-box 實驗性質

<length> (en-US)<percentage> (en-US) 是應用於元素的 content box.



fill 實驗性質

Use the fill-available inline size or fill-available block size, as appropriate to the writing mode.

max-content 實驗性質

The intrinsic preferred height.

min-content 實驗性質

The intrinsic minimum height.

available 實驗性質

The containing block height minus vertical margin, border and padding.

fit-content 實驗性質

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%;


CSS Box Sizing Module Level 3
# preferred-size-properties


BCD tables only load in the browser

See also