1 x HTML Page with Dynamic Input Field in Letter Design

I want a similar design/functionality for the letter (only letter) you can find here: [login to view URL] The background of the page should be GREY, the letter itself WHITE. It should have same input fields which are editable with a similar design (but not exactly 1:1 CLONE!). The input fields should be dynamic in size same as you can see on sample page for "Dein Name", "Straße", "PLZ Ort". The input field also should smoothly integrate in the design like on the example, and not shown as ordinary input fields. - You ONLY need to to the letter on grey background. NOT the complete page! - No 1:1 Copy Clone (own code) You will put a POST button, so that we can post input fields to next page.