A style.css file is a file that contains the Cascading Style Sheets (CSS) code that defines the appearance and layout of a web page¹. CSS is a language that describes how HTML elements should be displayed on screen, on paper, in speech, or on other media².

A style.css file can be created using any text editor, such as Notepad or Visual Studio Code. The file name should end with the .css extension, and the file should follow the CSS syntax and rules.

Here is an example of a simple style.css file that sets the background color of the body element to light blue, the color of the h1 element to white, and the font family and size of the p element to Verdana and 20px:

A style.css file can be linked to an HTML document using the element in the section. The element should have the following attributes:

• rel: Specifies the relationship between the HTML document and the linked resource. The value should be "stylesheet" for CSS files.

• type: Specifies the MIME type of the linked resource. The value should be "text/css" for CSS files.

• href: Specifies the URL of the linked resource. The value can be an absolute or relative path to the CSS file.

Here is an example of linking a style.css file to an HTML document: