Cascading Style Sheets (CSS) are the design foundation of most websites. It describes how the elements should be rendered on screen. This is where the CSS @import at-rule steps in to help. The @import rule tells the CSS engine to import an external style sheet into another style sheet. This allows style rules from a style sheet to be added to another style sheet. This rule can also be used in combination with media queries to import a style sheet based on the device type.