定位 · Bootstrap 6.0 中文文档

类名	样式
.position-static	position: static;
.position-relative	position: relative;
.position-absolute	position: absolute;
.固定位置	position: fixed;
.position-sticky	position: sticky;
.top-0	top: 0;
.top-50	top: 50%;
.top-100	top: 100%;
.bottom-0	bottom: 0;
.bottom-50	bottom: 50%;
.bottom-100	bottom: 100%;
.start-0	inset-inline-start: 0;
.start-50	inset-inline-start: 50%;
.start-100	inset-inline-start: 100%;
.end-0	inset-inline-end: 0;
.end-50	inset-inline-end: 50%;
.end-100	inset-inline-end: 100%;
.translate-middle	transform: translate(-50%, -50%);
.translate-middle-x	transform: translateX(-50%);
.translate-middle-y	transform: translateY(-50%);

位置值

提供快速定位类，但它们不具有响应性。

HTML

          <div class="position-static">...</div>
<div class="position-relative">...</div>
<div class="position-absolute">...</div>
<div class="position-fixed">...</div>
<div class="position-sticky">...</div>

排列元素

使用边缘定位工具轻松排列元素。格式是{property}-{position}。

其中 property 为以下之一：

top - 用于垂直top位置
start - 用于水平left位置（在从左到右中）
bottom - 用于垂直bottom位置
end - 用于水平right位置（在从左到右中）

其中 position 为以下之一：

0 - 用于0边缘位置
50 - 用于50%边缘位置
100 - 用于100%边缘位置

（你可以通过向 $position-values Sass map变量添加条目来增加更多位置值。）

HTML

<div class="position-relative">
  <div class="position-absolute top-0 start-0"></div>
  <div class="position-absolute top-0 end-0"></div>
  <div class="position-absolute top-50 start-50"></div>
  <div class="position-absolute bottom-50 end-50"></div>
  <div class="position-absolute bottom-0 start-0"></div>
  <div class="position-absolute bottom-0 end-0"></div>
</div>

居中元素

此外，你还可以使用变换工具类 .translate-middle 将元素居中。

此类将转换 translateX(-50%) 和 translateY(-50%) 应用于元素，结合边缘定位工具使用，可使元素绝对居中。

HTML

<div class="position-relative">
  <div class="position-absolute top-0 start-0 translate-middle"></div>
  <div class="position-absolute top-0 start-50 translate-middle"></div>
  <div class="position-absolute top-0 start-100 translate-middle"></div>
  <div class="position-absolute top-50 start-0 translate-middle"></div>
  <div class="position-absolute top-50 start-50 translate-middle"></div>
  <div class="position-absolute top-50 start-100 translate-middle"></div>
  <div class="position-absolute top-100 start-0 translate-middle"></div>
  <div class="position-absolute top-100 start-50 translate-middle"></div>
  <div class="position-absolute top-100 start-100 translate-middle"></div>
</div>

通过添加.translate-middle-x或.translate-middle-y类，元素只能在水平方向或垂直方向上定位。

HTML

<div class="position-relative">
  <div class="position-absolute top-0 start-0"></div>
  <div class="position-absolute top-0 start-50 translate-middle-x"></div>
  <div class="position-absolute top-0 end-0"></div>
  <div class="position-absolute top-50 start-0 translate-middle-y"></div>
  <div class="position-absolute top-50 start-50 translate-middle"></div>
  <div class="position-absolute top-50 end-0 translate-middle-y"></div>
  <div class="position-absolute bottom-0 start-0"></div>
  <div class="position-absolute bottom-0 start-50 translate-middle-x"></div>
  <div class="position-absolute bottom-0 end-0"></div>
</div>

示例

以下是这些类别的一些现实生活中的例子：

标记

HTML

<button type="button" class="btn-solid theme-primary position-relative">
  Mails <span class="position-absolute top-0 start-100 translate-middle badge rounded-pill theme-secondary theme-contrast">+99 <span class="visually-hidden">unread messages</span></span>
</button>

<div class="position-relative py-2 px-4 theme-secondary theme-contrast border border-secondary rounded-pill">
  Marker <svg width="1em" height="1em" viewBox="0 0 16 16" class="position-absolute top-100 start-50 translate-middle mt-1" fill="var(--bs-theme-bg)" xmlns="http://www.w3.org/2000/svg" aria-hidden="true"><path d="M7.247 11.14L2.451 5.658C1.885 5.013 2.345 4 3.204 4h9.592a1 1 0 0 1 .753 1.659l-4.796 5.48a1 1 0 0 1-1.506 0z"/></svg>
</div>

<button type="button" class="btn-solid theme-primary position-relative">
  Alerts <span class="position-absolute top-0 start-100 translate-middle w-1 h-1 border border-bg rounded-circle bg-danger p-2"><span class="visually-hidden">unread messages</span></span>
</button>

你可以将这些类与现有组件一起使用来创建新的组件。请记住，你可以通过向 $position-values 变量添加条目来扩展其功能。

HTML

<div class="position-relative m-4">
  <div class="progress" role="progressbar" aria-label="Progress" aria-valuenow="50" aria-valuemin="0" aria-valuemax="100" style="height: 1px;">
    <div class="progress-bar" style="width: 50%"></div>
  </div>
  <button type="button" class="position-absolute top-0 start-0 translate-middle btn-solid btn-sm theme-primary rounded-pill" style="width: 2rem; height:2rem;">1</button>
  <button type="button" class="position-absolute top-0 start-50 translate-middle btn-solid btn-sm theme-primary rounded-pill" style="width: 2rem; height:2rem;">2</button>
  <button type="button" class="position-absolute top-0 start-100 translate-middle btn-solid btn-sm theme-secondary rounded-pill" style="width: 2rem; height:2rem;">3</button>
</div>

CSS

Sass map

默认位置工具类值在 Sass map中声明，然后用来生成我们的工具类。

scss/_config.scss

$position-values: ();
// stylelint-disable-next-line scss/dollar-variable-default
$position-values: defaults(
  (
    0: 0,
    50: 50%,
    100: 100%
  ),
  $position-values
);

Sass 工具 API

位置工具在我们的工具 API scss/_utilities.scss 中声明。了解如何使用工具 API。

scss/_utilities.scss

"position": (
  property: position,
  values: static relative absolute fixed sticky
),
"top": (
  property: top,
  values: $position-values
),
"bottom": (
  property: bottom,
  values: $position-values
),
"start": (
  property: inset-inline-start,
  class: start,
  values: $position-values
),
"end": (
  property: inset-inline-end,
  class: end,
  values: $position-values
),
"translate-middle": (
  property: transform,
  class: translate-middle,
  values: (
    null: translate(-50%, -50%),
    x: translateX(-50%),
    y: translateY(-50%),
  )
),