Active states on numbered buttons

[dustinusey]

Step Two in the UI shows three buttons: "3", "5", "10". By default, "3" is chosen. As a user makes a selection, the new number of questions is updated in the code and works as expected to create the right sized quiz, but there is no way to let the user know how many questions are going to be generated. All of the buttons remain gray regardless of which button is active.

Update the code to add a bit of logic that gives some tailwind classes to the correct button that's active.

tailwind classes to add:
"bg-indigo-500 text-white"