如何获得滚动式flexbox父级中最后一个子级的下边距显示？

Question

在下面的界面中，（上一个）.panel（使用flex设置样式）将不会滚动到上一个（子）.item的底部边缘下方，即使最后一个.item（像所有其他）的margin-bottom应该为12px。

这就是我要实现的目标：

当我向下滚动时，我想查看最后一个12px的.item底边距。

这里是界面：

.interface {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  padding: 60px 0;
  font-family: sans-serif;
  color: rgb(255, 255, 255);
  background-color: rgb(159, 0, 0);
  opacity: 1;
}

.header,
.footer {
  position: fixed;
  left: 0;
  z-index: 12;
  width: 100%;
  height: 60px;
  line-height: 60px;
  text-align: center;
  background-color: rgb(159, 0, 0);
  box-shadow: 0 0 6px rgba(15, 0, 0, 0.4);
}

.header {
  top: 0;
}

.heading {
  margin: 0;
  padding: 0;
}

.footer {
  bottom: 0;
}

.credit {
  margin: 0;
  padding: 0;
}

.intro {
  height: 60px;
  margin: 0;
  padding: 0;
  line-height: 60px;
  font-size: 20px;
  text-transform: uppercase;
  text-align: center;
  background-color: rgba(127, 0, 0, 0.4);
  box-shadow: 0 0 6px rgba(15, 0, 0, 0.4);
}

.panel {
  display: flex;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  height: calc(100vh - 180px);
  padding-top: 12px;
  overflow-y: scroll;
  box-sizing: border-box;
  transform: translateY(0);
}

.item {
  flex: 0 1 30vw;
  height: 160px;
  margin: 12px;
  line-height: 160px;
  text-align: center;
  text-shadow: 1px 1px 1px rgba(31, 0, 0, 0.4);
  background-color: rgba(47, 0, 0, 0.4);
  border: 1px solid rgb(95, 0, 0);
}


@media only screen and (max-width: 906px) {

  .item {
    flex: 0 1 44vw;
  }
}


@media only screen and (max-width: 590px) {

  .item {
    flex: 0 1 96vw;
  }
}

<aside class="interface">

<header class="header">
<h2 class="heading">Title</h2>
</header>

<p class="intro">Text-based introduction here.</p>

<div class="panel">
<div class="item">Item 1</div>
<div class="item">Item 2</div>
<div class="item">Item 3</div>
<div class="item">Item 4</div>
<div class="item">Item 5</div>
<div class="item">Item 6</div>
<div class="item">Item 7</div>
<div class="item">Item 8</div>
<div class="item">Item 9</div>
</div>

<footer class="footer">
<p class="credit">Credit</p>
</footer>

</aside>

N.B。打开上方的Code Snippet到整页。

Answer 1

解决此问题的一种方法是使用::after伪元素，如下所示：

.panel::after {
  content: '';
  display: block;
  width: 100vw;
  height: 12px;
  background-color: transparent;
}

这将重新创建不会显示的12px底部页边空白。

由于包括::after伪元素的唯一原因是作为“ helper”，这有点不明智。 （但仍然比包装器<div>更具吸引力。）

具有::after伪元素的接口的工作示例：

.interface {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  padding: 60px 0;
  font-family: sans-serif;
  color: rgb(255, 255, 255);
  background-color: rgb(159, 0, 0);
  opacity: 1;
}

.header,
.footer {
  position: fixed;
  left: 0;
  z-index: 12;
  width: 100%;
  height: 60px;
  line-height: 60px;
  text-align: center;
  background-color: rgb(159, 0, 0);
  box-shadow: 0 0 6px rgba(15, 0, 0, 0.4);
}

.header {
  top: 0;
}

.heading {
  margin: 0;
  padding: 0;
}

.footer {
  bottom: 0;
}

.credit {
  margin: 0;
  padding: 0;
}

.intro {
  height: 60px;
  margin: 0;
  padding: 0;
  line-height: 60px;
  font-size: 20px;
  text-transform: uppercase;
  text-align: center;
  background-color: rgba(127, 0, 0, 0.4);
  box-shadow: 0 0 6px rgba(15, 0, 0, 0.4);
}

.panel {
  display: flex;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  height: calc(100vh - 180px);
  padding-top: 12px;
  overflow-y: scroll;
  box-sizing: border-box;
  transform: translateY(0);
}

.item {
  flex: 0 1 30vw;
  height: 160px;
  margin: 12px;
  line-height: 160px;
  text-align: center;
  text-shadow: 1px 1px 1px rgba(31, 0, 0, 0.4);
  background-color: rgba(47, 0, 0, 0.4);
  border: 1px solid rgb(95, 0, 0);
}

.panel::after {
  content: '';
  display: block;
  width: 100vw;
  height: 12px;
  background-color: transparent;
}


@media only screen and (max-width: 906px) {

  .item {
    flex: 0 1 44vw;
  }
}


@media only screen and (max-width: 590px) {

  .item {
    flex: 0 1 96vw;
  }
}

<aside class="interface">

<header class="header">
<h2 class="heading">Title</h2>
</header>

<p class="intro">Text-based introduction here.</p>

<div class="panel">
<div class="item">Item 1</div>
<div class="item">Item 2</div>
<div class="item">Item 3</div>
<div class="item">Item 4</div>
<div class="item">Item 5</div>
<div class="item">Item 6</div>
<div class="item">Item 7</div>
<div class="item">Item 8</div>
<div class="item">Item 9</div>
</div>

<footer class="footer">
<p class="credit">Credit</p>
</footer>

</aside>

N.B。打开上方的Code Snippet到整页。