如何在Angular中更改前/后樣式？

我正在嘗試在CSS中使用before/after實現帶有三角形的面包屑，如本教程所示:

http://css-tricks.com/triangle-breadcrumbs/

相關片段:

.breadcrumb li a {
  color: white;
  text-decoration: none;
  padding: 10px 0 10px 65px;
  background: hsla(34, 85%, 35%, 1);
  position: relative;
  display: block;
  float: left;
}

.breadcrumb li a:after {
  content: " ";
  display: block;
  width: 0;
  height: 0;
  border-top: 50px solid transparent;
  border-bottom: 50px solid transparent;
  border-left: 30px solid hsla(34, 85%, 35%, 1);
  position: absolute;
  top: 50%;
  margin-top: -50px;
  left: 100%;
  z-index: 2;
}

<ul class="breadcrumb">
  <li><a href="#">Home</a></li>
</ul>