.wp-block-separator {
  margin: 20px 0 !important;
}
.wp-block-separator.aligncenter {
  margin: 20px auto !important;
}
.wp-block-separator.is-style-accent {
  border-width: 12px;
  width: 75px;
  margin: 20px auto !important;
}
.wp-block-separator.is-style-accent:not(.aligncenter) {
  margin: 20px 0 !important;
}