An import Style Sheet is a sheet that can be imported to combined with another style sheet. This allows creating one main sheet containing declarations that apply to the whole site. It also allows partial sheets containing declaration that apply to specific elements or document. By importing partial sheets to one main sheet, multiple style sheets can be combined into one.
File: Main.css (Combining Style1.css and Style2.css)
File: Example.html (File using the main.css style )
Consider one more situation, where a document requires style information from main.css and one more stylesheet, say, style3.css. The document that additionally requires the style3.css information can be written in the following way: