build a webapp that looks like native mobile app

Build a webapp that has: 1) user registration (account must bee approved by backend admin) 2) user login 3) admin management 4) logged in user can submit 1 form (predefined form with words and textfields etc.). The form will require to collect 2 to 5 signatures (using tablets or phones to sign). Upon submitting the form, generate PDF of the form to sent to the parties. 5) store the form in backend RDMS. postgreSQL preferred. 6) make use of HTML, CSS, PHP for this webapp. web template for frontend and admin is ok. or recommend other language or platform that u think is better (can consider RoR) This is just for 1 form. If done well, will award for the other forms.