.nav-accordion .nav-group { margin-bottom: 8px; }
.nav-accordion .nav-toggle { width: 100%; text-align: left; position: relative; }
.nav-accordion .nav-toggle::after {
  content: '▸'; position: absolute; right: 12px; top: 50%; transform: translateY(-50%); opacity: .7;
}
.nav-accordion .nav-group.open .nav-toggle::after { content: '▾'; }
.nav-accordion .subnav-wrap { display: none; }
.nav-accordion .nav-group.open .subnav-wrap { display: block; }