I dig it
I bet you had a lot of trouble trying to get the bootstrap stuff to work correctly, didn’t you? That’s because you didn’t include the bootstrap links in the top of your html file! You’ll want to include
<!-- Latest compiled and minified CSS -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<!-- jQuery library -->
at the top of your html file. Now you’ll have access to all of the classes you were trying to use (and having to build some of them manually in your CSS). Doing this should make your site way more responsive by default, and you can make tweaks from there.
p.s. It looks really good for having written all of the styling yourself. This should certainly help though!