Need a Style Editor For Bootstrap with Live Preview

Hello We need to make a style editor for bootstrap where user can edit the bootstrap css through HTML forms. We need a live preview like it is on the website [login to view URL] We do want the full app we just need the preview same as the [login to view URL] where by the user can see the websites in mobile, tablet and desktop. So we need the style css to be generated dynamically. SO users can dynamically change headers, footers, navigations, Sliders. Body Background etc... Thanks