CSS Lint is a tool to help point out problems with your CSS code. It does basic syntax checking as well as applying a set of rules to the code that look for problematic patterns or signs of inefficiency. The rules are all pluggable, so you can easily write your own or omit ones you don’t want.
By default, CSS Lint shows any parsing errors. Parsing errors usually mean you mistyped a character and may cause the browser to drop your rule or a property. Parsing errors are presented as errors by CSS Lint, the most important issues to fix.