Media queries allows to define style for a certain configuration only. By default the CSS is used for all configuration. Examples: media="print" media="screen". They can be applied to entire files or group of rules inside the file.
I recommend always using size @media screen and (min-width: 960px) {. And never device size @media screen and (min-device-width: 960px) {
https://github.com/you-dont-need/You-Dont-Need-JavaScript
https://codepen.io/viduthalai1947/pen/JkhDK