There are plenty of resources on the topic, just search for it.
The simplest media query syntax looks like this:
@media media-type and (media-feature-rule) { /* CSS rules go here */ }
It consists of:
- A media type, which tells the browser what kind of media this code is for (e.g. print, or screen).
- A media expression, which is a rule, or test that must be passed for the contained CSS to be applied.
- A set of CSS rules that will be applied if the test passes and the media type is correct.