.ui-select__multi + .ui-select__options .option:after {
  float: right;
  display: block;
  content: '';
  background: transparent;
  border: 1px solid #1abf7a;
  border-radius: 30px;
  height: 15px;
  width: 15px;
}

.ui-select__multi + .ui-select__options .option[checked]:after,
.ui-select__multi + .ui-select__options .option.checked:after {
  background: #1abf7a;
}