Dimming the main window

We could simply hide our main window when the modal is open, but it's better if the user can still be aware of where they are in flow of the app. To achieve this, we will dim the main window under a semi-transparent panel.

We can do this by giving our modal panel an opaque black background.

style.css:

#modal {
  ...
  background-color: rgba(0,0,0,0.85);
}