Overleaf/services/web/frontend/stylesheets/components/caret.scss

:root {
  --caret-width-base: 4px;
}

.caret {
  display: inline-block;
  width: 0;
  height: 0;
  margin-left: 2px;
  vertical-align: middle;
  border-top: var(--caret-width-base) solid;
  border-right: var(--caret-width-base) solid transparent;
  border-left: var(--caret-width-base) solid transparent;
  margin-top: calc(-1 * var(--caret-width-base) / 2);
}