You can automatically check a cascading style sheet (CSS) to ensure that its
grammar and syntax are valid. For a description of what constitutes a valid
CSS, see:
To check a CSS:
In the Files window, right-click the CSS node.
Choose Check CSS.
The Output window lists any errors in the CSS
grammar along with the line number where the error was detected.
This location is not necessarily the line where
the error occurred. You can double-click any error message to go to the
line in the CSS file where the error was detected.