Implementation in RoR project of existing design for simple web app interface

We are creating a primarily mobile adapted web application in the RoR framework. We have a complete design for all of the 27 screens of the app interface in png format, which we need to implement in the frontend of our RubyOnRails project using CSS, HTML, and JavaScript. The design is primarily mobile adapted so should be responsive, and should take different sizes and types of mobile screens into account. It should also work well on desktop. We have used Bootstrap previously for our mash-up design, and think it might be a suitable framework to use for this implementation as well, but we are also open to using other similar Java-libraries. Our own backend developer will be available to make sure that the frontend implementation is coordinated with all relevant backend functionality, and no backend programming will be required for this job. We are only interested in hiring an experienced frontend developer with good skills in CSS, HTML and JavaScript, and who also has good skills for frontend-implementation in RoR. If we think that you seem to be an interesting candidate for the job, we will let you do a preliminary minor sample work to ensure your competence in the above requirements. This sample work should not take longer then 30 minutes for someone with sufficient skills for our requirement, and will be payed accordingly. We are looking to contract a competent freelancer for this job as soon as possible. Ideally it should be someone who has some time to put into this from the start, and who could complete the work within a couple of weeks. Looking forward to hear from you! Team Musing®