延伸链接（Stretched link）
通过 CSS “延伸” 嵌套链接，使任何 HTML 元素或 Bootstrap 组件都可点击。
在链接中添加 .stretched-link，可通过 ::after 伪元素使其包含块可被点击。在大多数情况下，这意味着带有position: relative;的元素包含一个带有.stretched-link类的链接时，该链接是可点击的。请注意，鉴于 CSS position 的工作原理，.stretched-link 不能与大多数表格元素混合使用。
在 Bootstrap 中，卡片默认具有 position: relative，因此在这种情况下，您可以放心地将.stretched-link 类添加到卡片中的链接上，而无需更改任何其他 HTML 代码。
延伸链接不建议使用多个链接和分接目标。不过，如果需要，一些 position 和 z-index 样式可以提供帮助。
Card with stretched link
Some quick example text to build on the card title and make up the bulk of the card's content.
Go somewhere<div class="card" style="width: 18rem;">
<img src="..." class="card-img-top" alt="...">
<div class="card-body">
<h5 class="card-title">Card with stretched link</h5>
<p class="card-text">Some quick example text to build on the card title and make up the bulk of the card's content.</p>
<a href="#" class="btn btn-primary stretched-link">Go somewhere</a>
</div>
</div>大多数自定义组件默认情况下都没有 position: relative，因此我们需要在此处添加 .position-relative，以防止链接超出父元素的范围。
Custom component with stretched link
This is some placeholder content for the custom component. It is intended to mimic what some real-world content would look like, and we're using it here to give the component a bit of body and size.
Go somewhere<div class="d-flex position-relative">
<img src="..." class="flex-shrink-0 me-3" alt="...">
<div>
<h5 class="mt-0">Custom component with stretched link</h5>
<p>This is some placeholder content for the custom component. It is intended to mimic what some real-world content would look like, and we're using it here to give the component a bit of body and size.</p>
<a href="#" class="stretched-link">Go somewhere</a>
</div>
</div>Columns with stretched link
Another instance of placeholder content for this other custom component. It is intended to mimic what some real-world content would look like, and we're using it here to give the component a bit of body and size.
Go somewhere<div class="row g-0 bg-body-secondary position-relative">
<div class="col-md-6 mb-md-0 p-md-4">
<img src="..." class="w-100" alt="...">
</div>
<div class="col-md-6 p-4 ps-md-0">
<h5 class="mt-0">Columns with stretched link</h5>
<p>Another instance of placeholder content for this other custom component. It is intended to mimic what some real-world content would look like, and we're using it here to give the component a bit of body and size.</p>
<a href="#" class="stretched-link">Go somewhere</a>
</div>
</div>确定包含的区块
如果延伸链接似乎不起作用，包含块 很可能就是原因所在。以下 CSS 属性将使一个元素成为包含块：
- 非
static的position值 - 非
none的transform或perspective值 transform或perspective的will-change值- 非
none的filter值，或者filter的will-change值（仅适用于 Firefox）。
Card with stretched links
Some quick example text to build on the card title and make up the bulk of the card's content.
Stretched link will not work here, because position: relative is added to the link
This stretched link will only be spread over the p-tag, because a transform is applied to it.
<div class="card" style="width: 18rem;">
<img src="..." class="card-img-top" alt="...">
<div class="card-body">
<h5 class="card-title">Card with stretched links</h5>
<p class="card-text">Some quick example text to build on the card title and make up the bulk of the card's content.</p>
<p class="card-text">
<a href="#" class="stretched-link text-danger" style="position: relative;">Stretched link will not work here, because <code>position: relative</code> is added to the link</a>
</p>
<p class="card-text bg-body-tertiary" style="transform: rotate(0);">
This <a href="#" class="text-warning stretched-link">stretched link</a> will only be spread over the <code>p</code>-tag, because a transform is applied to it.
</p>
</div>
</div>