<div class="demo-content">Demo Content</div>

.demo-content {
  position: relative; 
  background-color: #000;
  color: #fff;
  padding: 10px 20px;
  border-radius: 6px;
} 

.demo-content::after {
  position: absolute;
  font-size: 2em;
  color: #000;
  content: "▾";
  text-align: center;
  top: 23px;
  left: 50%;
}