I was hired to convert the NFL Virtual Tailgate website (a Joomla website), into a responsive website.
Creating a responsive template from the ground up is much less complicated than converting a website to be responsive. There is a lot of work involved in a conversion and a lot of trial error. I basically took the template and dropped it into Bootstrap 3. From there, I had to go into all of the modules and articles and reformat them as they were built using old style tables.