Mobile first 'Single landing page' using flexbox again

I just want to say that this one took it's time. Had to re-write everything (probably twice) from scratch because I was not satisfied with the solution I came up with. I hope the current solution is worth the time. Also, before this, I didn't know how to use the font-awesome icons so that was something new. I cannot use that properly even now. The default icons were kinda italicized and I just replaced the <i> with <b> and I don't know whether that was correct or not. And there were a few more things I guess.