inset-block-start

Baseline Widely available *

This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2021.

* Some parts of this feature may have varying levels of support.

CSS 属性 inset-block-start 定义了元素的块首偏移，并根据元素的书写模式、行内方向和文本朝向对应至实体偏移。根据 writing-mode、direction 和 text-orientation 所定义的值，此属性对应于 top、right、bottom 或 left 属性。

尝试一下

writing-mode: horizontal-tb;

writing-mode: vertical-rl;

writing-mode: horizontal-tb;
direction: rtl;

writing-mode: vertical-lr;

<section id="default-example">
  <div class="example-container" id="example-element">
    <div id="abspos">
      I am absolutely positioned with inset-block-start: 50px
    </div>
    <p>
      As much mud in the streets as if the waters had but newly retired from the
      face of the earth, and it would not be wonderful to meet a Megalosaurus,
      forty feet long or so, waddling like an elephantine lizard up Holborn
      Hill.
    </p>
  </div>
</section>

#example-element {
  border: 0.75em solid;
  padding: 0.75em;
  position: relative;
  width: 100%;
  min-height: 200px;
  unicode-bidi: bidi-override;
}

#abspos {
  background-color: yellow;
  color: black;
  border: 3px solid red;
  position: absolute;
  inset-block-start: 50px;
  inline-size: 140px;
}

语法

css
/* 长度值 */
inset-block-start: 3px;
inset-block-start: 2.4em;

/* 包含块的宽度或高度的百分比 */
inset-block-start: 10%;

/* 关键词值 */
inset-block-start: auto;

/* 全局值 */
inset-block-start: inherit;
inset-block-start: initial;
inset-block-start: revert;
inset-block-start: revert-layer;
inset-block-start: unset;

取值

inset-block-start 属性的取值与 left 属性相同。

形式定义

初始值auto
适用元素positioned elements
是否是继承属性否
Percentageslogical-height of containing block
计算值same as box offsets: top, right, bottom, left properties except that directions are logical
动画类型a length, percentage or calc();

形式语法

inset-block-start = 
  auto                 |
  <length-percentage>  

<length-percentage> = 
  <length>      |
  <percentage>

示例

设置块首偏移

HTML

html
<div>
  <p class="exampleText">示例文本</p>
</div>

CSS

css
div {
  background-color: yellow;
  width: 120px;
  height: 120px;
}

.exampleText {
  writing-mode: vertical-lr;
  position: relative;
  inset-block-start: 20px;
  background-color: #c8c800;
}

结果

规范

Specification
CSS Logical Properties and Values Level 1
# propdef-inset-block-start
CSS Positioned Layout Module Level 3
# propdef-inset-block-start

浏览器兼容性

参见