Placeholders instead of labels in forms
I've been working on a similar goal but I've been working in WordPress. I followed the advice given to me and added Caldera Forms with CF-CiviCRM. CF-CiviCRM is WordPress plugin that functions as a bridge between Calder Forms and CiviCRM. I fully appreciate that you are currently in Drupal. You really need to decide if you are on the right platform for your ultimate goal. If you have the coding chops to pull this off, keep going the way you are going. On the other hand, if you want an existing solution to the problem you've presented, Wordpress with CiviCRM and Caldera Forms is a very workable solution.