.wp-block-wpseopress-table-of-contents nav ol {
  list-style: none; 
  padding-left: 0; 
  counter-reset: list-counter; 
}

.wp-block-wpseopress-table-of-contents nav ol li {
  counter-increment: list-counter; 
  margin-bottom: 0.5em; 
}

.wp-block-wpseopress-table-of-contents nav ol li::before {
  content: "# " counter(list-counter) " "; 
  font-weight: normal; 
  color: #000; 
}