Why this error arises csslint expected rebrace at line ?

<pre>

 @import url("https://fonts.googleapis.com/css?family=Source+Sans+Pro:300,400,700,400italic");
    :root
{
    --blue: #158CBA;
    --indigo: #6610f2;
    --purple: #6f42c1;
    --pink: #e83e8c;
    --red: #FF4136;
    --orange: #fd7e14;
}