Responsive with mediQuery, Form with html css and Js.

Nice!

Since you're looking for feedback, here it is.

1. Set the font the same as given in the style guide.
2. Set a background to the body as given in the design.
3. Use the following code to center the form to the page:

body {
min-height: 100vh;
display: flex;
justify-content: center;
align-items: center;
}

When you submit the newsletter a 405 page will be displayed please just refresh, it a bug from github.