CodePudding user response：

Try this:

 <link href="~/FolderName/Petvrs.css" rel="stylesheet" />

Or drag and drop this css file inside HTML page it's must work.

CodePudding user response：

The CSS rules you have specified does not match any elements in your HTML. I cannot find any element with the class callout, for example. And the CSS rule ul#menuItems li does not match any element. Which element(s) do you expect to be modified by your CSS?