Center a Pseudo Element

Center a "triangle" that was created with pseudo:after.

HTML

<div class="thing">
    <hp-tooltip open="left">
        <hp-icon font="question"></hp-icon>
        <hp-tooltip-bubble ng-show="show">
        
        </hp-tooltip-bubble>
    </hp-tooltip>
    <div>Other content here</div>
</div>

CSS

.thing {
    padding: 100px;
}
hp-tooltip {
  position: relative;
  display: inline-block;
  width: 16px;
}
hp-tooltip > hp-icon[font="question"] {
  border-radius: 50%;
  display: inline-block;
  width: 16px;
  height: 16px;
  background-color: #0069E9;
  color: #ffffff;
  font-size: 14px;
  letter-spacing: 1px;
  line-height: 1.5;
  text-align: center;
}