Firefox proton context-navigation customization

/*contextmenu right-click pg*/
#context-navigation menuitem {
  color: #9f1aff !important;
  transition: color 300ms cubic-bezier(0.645, 0.045, 0.355, 1) !important;
}
#context-navigation menuitem:hover {
  color: #00DDFF !important;
  background: none !important;
}
#context-navigation
    > .menuitem-iconic
    > .menu-iconic-left
    > .menu-iconic-icon {
    background-color: transparent !important;
}