如何使用 css 在 font awesome 图标中创建不同角度的边框?

How to create border with different angles in font awesome icons using css?

我想制作一个字体真棒图标的边框,就像这样。
如何使用css? Screenshot

见下文。希望这有帮助。

.icon-container {
  background: darkgreen;
  color: white;
  width: 3rem;
  height: 3rem;
  display: flex;
  justify-content: center;
  align-items: center;
  position: relative;
}

.icon-container::after {
  content: "";
  background: darkgreen;
  width: 1rem;
  height: 1rem;
  position: absolute;
  bottom: -5px;
  left: calc( 50% - 0.5rem);
  transform: rotate(45deg);
}
<link href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet" />
<div class="icon-container">
  <i class="fa fa-car fa-2x" aria-hidden="true"></i>
</div>