Resolve "Adjust stylings to display input fields underneath each other"

Closes #69 (closed)

Proposed changes

Input fields are now displayed underneath each other and with full width. Width will later be limited due to component width.

How to test

Insert any formular component to app.component.html.

The free room left of the formular comes from the router-outlet element, which isn't used yet. Removing it from the app.component.html centers the form.