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位置 (Position)

使用速記通用類別配置元素的位置。

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定位值

可以快速的使用位置類別定位，儘管它們並不是響應式的。

<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

可以使用邊界定位通用類別輕鬆的排列元素。格式為 {property}-{position}。

其中，property 為以下的其中一種:

top - 用於垂直定位 top
start - 用於水平定位 left (LTR)
bottom - 用於垂直定位 bottom
end - 用於水平定位 right (LTR)

其中，position 為以下的其中一種:

0 - 用於 0 的邊界定位
50 - 用於 50% 的邊界定位
100 - 用於 100% 的邊界定位

(你可以透過在 $position-values Sass map 變數添加實體，以增加更多定位值。)

<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>

元素置中

此外，你也可以透過轉換通用類別 .translate-middle 將元素置中。

此類別將 transform 之 translateX(-50%) 與 translateY(-50%) 應用於元素，並結合使用邊界定位通用類別，讓你可以把元素完全置中。

<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>

透過添加 .translate-middle-x 或 .translate-middle-y 類別，元素將只能在水平或垂直方向上定位。

<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>

範例

以下是這些類別的實際案例:

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

<button type="button" class="btn btn-dark position-relative">
  Marker <svg width="1em" height="1em" viewBox="0 0 16 16" class="position-absolute top-100 start-50 translate-middle mt-1 bi bi-caret-down-fill" fill="#212529" xmlns="http://www.w3.org/2000/svg"><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>
</button>

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

可以將這些類別與現有的元件結合使用，創造新的元件。請記得你可以透過在 $position-values 變數添加實體以擴展它的功能。

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

Sass

Maps

Default position utility values are declared in a Sass map, then used to generate our utilities.

$position-values: (
  0: 0,
  50: 50%,
  100: 100%
);

Utilities API

Position utilities are declared in our utilities API in scss/_utilities.scss. Learn how to use the utilities API.

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