frdh-mmenu-js/dist/addons/keyboardnavigation/mmenu.keyboardnavigation.css

.mm-menu_keyboardfocus a:focus,.mm-menu_keyboardfocus.mm-menu_opened~.mm-wrapper__blocker a:focus{background:rgba(255,255,255,.4);background:var(--mm-color-background-emphasis);outline:0}.mm-wrapper__blocker .mm-tabstart{cursor:default;display:block;width:100%;height:100%}.mm-wrapper__blocker .mm-tabend{opacity:0;position:absolute;bottom:0}