.simplecolorpicker div.selected:after {
  font-family: 'Font Awesome 5 Free';
  font-weight: 900;
  -webkit-font-smoothing: antialiased;
  color:black;
  text-shadow: -1px -1px 0 #fff, 1px -1px 0 #fff, -1px 1px 0 #fff, 1px 1px 0 #fff;
  content: '\f00c'; /* Ok/check mark */
  margin-left: -11px;
  font-size: 11px;
}