I require some dynamic and responsive images for our web portal

Hi, I'm the Head of IT for a SME on the Isle of Man. Although I run a small development team, the skill set is deep and narrow and mostly focused around the back-end of our proprietary ERP system. The software development needs for the company has reached a stage where we need to start using external web stack developers to help with web based projects. As this is my first Freelancer project, I thought it would be best to keep it small in an attempt to firstly familiarize myself with the process and secondly to build a network of developers that can be used for future projects. The specifics for this first project is very simple. I require a solution for a staged sign-on banner which we have implemented using multiple images at the different stages of the sign-on process. Unfortunately, this design has a flaw insomuch as the wording on the image gets distorted on certain device sizes. I would like a solution for this which will seamlessly handle and respond to the different screen sizes. Please see the images attached which will be self explanatory. At the moment we programmatically change to the relevant image at the specific stage of the sign-on process. I would prefer a solution in CSS3/ SASS.