The idea of the exercise is to add functionality to the "Toggle theme" button. We want the button to toggle between a dark and a light theme. Also, the current theme should be displayed on the title. The light theme is already developed.
Remember to save (Ctrl+s) frecuently, and make sure to save before refreshing the test browser (The one that appear on the right)
Once you start modifying the code, a new url should be generated just for your code.