.md-header__button.md-logo img {
    height: 56px;
    width: auto;
}

.md-nav__item--section > .md-nav__link {
  font-weight: 700;              /* stronger bold */
  text-transform: uppercase;    /* optional */
  letter-spacing: 0.05em;       /* optional */
  color: var(--md-primary-fg-color);
}

/* Add spacing before each section */

.md-nav__item--section {
  margin-top: 1rem;
}

Optional: subtle divider line

.md-nav__item--section:not(:first-child) {
  border-top: 1px solid rgba(0,0,0,.08);
  padding-top: 0.5rem;
}

/* Indent child nav items for clearer hierarchy */

/* .md-nav__item .md-nav {
  padding-left: 1rem;
} */

.md-nav__item--section > .md-nav {
  padding-left: 1rem;
}