.site-nav .nav-left .nav-icon {
  color: #000;
  display: inline-flex;
  align-items: center;
}

.site-nav .nav-left .github-mark {
  width: 24px;
  height: 24px;
  margin-right: 12px;
  transition: opacity .2s ease-in-out;
}

.site-nav .nav-left .nav-icon:hover .github-mark { opacity:.75; }