Usually a good idea to add a line-height as well, although it’s a personal preference how the line height is done, some will do it in a px value or em value. The media query will also depend on what screen size you are editing font sizes for as well. The example above means that any screen size from 0 to 480px (generally a landscape view on a phone), your font sizes will be what you see in the example.
The above example can also be used for anything else you need to adjust at that screen size.
With our premium themes, we offer access to site documentation, video tutorials and timely support. Even if you have just started on WordPress, our support staff have the patience to help you create appealing sites gracefully.