HTML5/SCSS/TypeScript Newsletter Sign-Up Form with Success Message

I've just completed my first challenge using TypeScript. The transition from JS to TS was quite a relief: working with weakly typed languages feels like trying to blindly maneuver through a minefield! The IDE can help but it only goes so far. I intend to only use TS from this moment forward on my web apps.

This project builds up on previous challenges and doesn't present a big step up in difficulty for those who managed to build the solutions for the previous ones.