WordPress/wp-includes/blocks/separator/style.css

@charset "UTF-8";
.wp-block-separator{
  border:1px solid;
  border-left:none;
  border-right:none;
}
.wp-block-separator.is-style-dots{
  background:none !important;
  border:none;
  height:auto;
  line-height:1;
  text-align:center;
}
.wp-block-separator.is-style-dots:before{
  color:currentColor;
  content:"···";
  font-family:serif;
  font-size:1.5em;
  letter-spacing:2em;
  padding-left:2em;
}