WordPress/wp-includes/blocks/pullquote/theme.css

.wp-block-pullquote{
  border-bottom:4px solid;
  border-top:4px solid;
  color:currentColor;
  margin-bottom:1.75em;
}
.wp-block-pullquote cite,.wp-block-pullquote footer,.wp-block-pullquote__citation{
  color:currentColor;
  font-size:.8125em;
  font-style:normal;
  text-transform:uppercase;
}