.post-toc {
  grid-row: 1/3;
  position: sticky;
  top: 0;
  max-width: 400px;
  margin-top: 107px;
}

#toc-header {
  font-size: 26px;
}

.post-toc ul {
  list-style: none;
  padding-left: 0px;
}

.post-toc a {
  text-decoration: none;
  color: #555;
  display: block;
  border-left: solid 2px lightgray;
  font-size: 20px;
  padding: 8px;
  padding-left: 50px;
}

.post-toc a.active {
  border-left-style: solid;
  border-left-width: 2px;
  border-color: red;
  background-color: lightgray;
  color: black;
}