How can I get rid of the paddings and margins that come with the webform? What I did was use position: absolute to have them the way I want, but that is probably not a good idea. I tried to put padding and margin 0 everywhere, but Drupal seems to override my CSS or something.
You can override Drupals styling rules. Just use your browsers (Chrome, Firefox) developer tools to inspect elements for whats styling rules they have. Then override them in your themes stylesheet(s).