Change CSS based on
- orientation (portrait or landscape)
You can use and, and the comma , to indicate or and even the word not to have the full power of boolean expressions.
You can use @media queries inside a single style-sheet, or you can load different style-sheets base on the @media query.
Probably the most common thing to use @media queries for is to change the site depending on the width of the browser using the min-width and max-width fields, but you can also use the others listed above.
Of course you can also use it to check the media type: screen, print, etc.http://css-tricks.com/css-media-queries/