Responsive is a component that you supply us multiple size classes and we apply which ever class fits best based on the parent div.
This specific version is a knockout component. There are sibling components for other libraries.
Feel free to see the example here: https://snowcoders.github.io/responsive-knockout/example/
Resize your browser window and you will see the number of cells decrease (first 9, then 4 then 1) based on the width of the window.