h1,
h2,
h3,
h4,
h5,
h6 {
  font-weight: 800 !important; /* or 700, 900, etc. */
}

.md-typeset h2 {
  border-top: 1px solid var(--md-default-fg-color);
  padding-top: 0.75rem;
  margin-top: 2rem;
}