Pure CSS screen widths
Pure CSS defines breakpoints or thresholds for classifying screen widths. The built-in screen width definitions in Pure CSS are shown in the table below. Note however you can change these thresholds using tools on the Pure CSS web site.
In essence, these allow you to control at what screen widths the responsive behaviour takes effect and Woof! makes use of these thresholds for specifying its own behaviour as described in subsequent sections.