:root {
  --border-radius: 3px;
}

.button.dropdown::after {
  display: block;
  width: 0;
  height: 0;
  border: inset 0.4em;
  content: "";
  border-bottom-width: 0;
  border-top-style: solid;
  border-color: #fefefe transparent transparent;
  border-radius: var(--border-radius);
  position: relative;
  top: 0.4em;
  display: inline-block;
  float: right;
  margin-left: 1em;
}