Clearer visual hierarchy
.md-typeset h1 { font-size: 2.00rem; font-weight: 700; }

.md-typeset h2 {
  font-size: 1.90rem;           /* bigger jump from h3 */
  font-weight: 700;
  margin: 1.3em 0 .5em;
  border-bottom: 1px solid var(--md-default-fg-color--lightest); /* subtle underline */
  padding-bottom: .15em;
}

.md-typeset h3 {
  font-size: 1.35rem;           /* smaller than before */
  font-weight: 700;
  margin: 1.1em 0 .35em;
  text-underline: #0a0a0a;
  text-underline-style: single;
}

.md-typeset h4 {
  font-size: 0.95rem;           /* clearly below h3 */
  font-weight: 600;
  margin: 1em 0 .25em;
}

.md-typeset h5 {
    text-transform: none;
}