位置（Position）
使用這些速記實(shí)用程序可以快速配置元素的位置。
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定位值
可以快速的使用位置類別定位，盡管它們并不是響應(yīng)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松的排列元素。格式為{property}-{position}。
其中，property為以下的其中一種：
top- 用于垂直定位topstart- 用于水平定位left（LTR）bottom- 用于垂直定位bottomend- 用于水平定位right（LTR）
其中，position為以下的其中一種：
0- 用于0的邊界定位50- 用于50%的邊界定位100- 用于100%的邊界定位
（你可以透過在$position-values Sass map變數(shù)添加實(shí)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(zhuǎn)換通用類別.translate-middle將元素置中。
此類別將transform之translateX（-50%）與translateY（-50%）應(yīng)用于元素，并結(jié)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>示例
以下是這些類別的實(shí)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(xiàn)有的元件結(jié)合使用，創(chuàng)造新的元件。請記得你可以透過在$position-values變數(shù)添加實(shí)體以擴(kuò)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="25" 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.
"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%),
)
),