There are two ways of retrofitting a nonresponsive or fixed-width site/app. One way is using the Adaptive Web Design (AWD) technique that uses absolute units (that is, pixels). The other way is using RWD and transforming all pixel values to percentages with a very simple formula.
Regardless of which techniques we use, we are going to have to use a desktop-first approach since the site we're dealing with was built for wide screens only. This means that we're going to use the
max-width property in our media queries.
Before we look at both retrofitting techniques, we need a base page to start with.