Make Responsive an ASP.NET Web Site

Hello, I have to make responsive this website for a client of mine. [login to view URL] The website is developed with Asp.net technologies I need a freelancer able to modify the website layout (that is very old) and make it responsive, in order to visualize it form smartphone and tablets. The modifies has to be completed with SEO principles, because we don't want to loose the ranking obtained with Google today. p.s. the website is connected with a management software. No modifies to this connections. Summarizing: -Ridesign the layout -Make it responsive -Don't lose SEO ranking Please stay in the budget.