/* Make the first-level items (top-level) bold */
.md-nav__list > .md-nav__item > .md-nav__link {
    font-weight: bold;
  }
  
  /* Make second-level items normal weight */
  .md-nav__list > .md-nav__item > nav .md-nav__list > .md-nav__item > .md-nav__link {
    font-weight: normal;
  }