A dropdown menu is a toggleable menu that allows the user to choose one value from a predefined list,Highlight a specific dropdown item with the .active class (adds a blue background color),To disable an item in the dropdown menu, use the .disabled class (gets a light-grey text color and a "no-parking-sign" icon on hover),You can also create a "dropright" or "dropleft" menu, by adding the .dropright or .dropleft class to the dropdown element. Note that the caret/arrow is added automatically,If you want the dropdown menu to expand upwards instead of downwards, change the