CSS 属性 border-inline-start-width 定义了元素的逻辑行首的边框宽度，并根据元素的书写模式、行内方向和文本朝向对应至实体边框宽度。根据 {{CSSXref("writing-mode")}}、{{CSSXref("direction")}} 和 {{CSSXref("text-orientation")}} 所定义的值，此属性对应于 {{CSSXref("border-top-width")}}、{{CSSXref("border-right-width")}}、{{CSSXref("border-bottom-width")}} 或 {{CSSXref("border-left-width")}} 属性。

```css interactive-example-choice border-inline-start-width: thick; writing-mode: horizontal-tb;


```css interactive-example-choice
border-inline-start-width: thick;
writing-mode: vertical-rl;

```css interactive-example-choice border-inline-start-width: 4px; writing-mode: horizontal-tb; direction: rtl;


```html interactive-example
<section class="default-example" id="default-example">
  <div class="transition-all" id="example-element">
    This is a box with a border around it.
  </div>
</section>

```css interactive-example

example-element {

background-color: palegreen; color: #000; border: 0 solid crimson; padding: 0.75em; width: 80%; height: 100px; unicode-bidi: bidi-override; }


## 语法

```css
/* 边框宽度值 */
border-inline-start-width: 5px;
border-inline-start-width: thick;

/* 全局值 */
border-inline-start-width: inherit;
border-inline-start-width: initial;
border-inline-start-width: revert;
border-inline-start-width: revert-layer;
border-inline-start-width: unset;

与此相关的属性有 {{CSSXref("border-block-start-width")}}、{{CSSXref("border-block-end-width")}} 和 {{CSSXref("border-inline-end-width")}}，这些属性定义了元素其他边框的宽度。

取值

<'border-width'>
- : 边框宽度。见 {{CSSXref("border-width")}}。

形式定义

形式语法

示例

HTML

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

CSS

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

.exampleText {
  writing-mode: vertical-lr;
  border: 1px solid blue;
  border-inline-start-width: 5px;
}