Cacher is the code snippet organizer for pro developers

<span id="demo15">文字内容</span>

<style>
#demo15{
  position: relative;
}
#demo15:after {
  border: 10px solid transparent;
  border-left: 10px solid #f00;
  width: 0;
  height: 0;
  position: absolute;
  content: ' '
}
</style>