I wanted to apply a rule to all classes beginning with a certain string.

/* any element with class that starts with 'col-' ex. 'col-sm-12' */
*[class^='col-']{ 
}

/* any element with a class that contains 'col-' ex. 'abc-col-123' */
*[class*='col-']{ 
}

Related External Links:

• Stack Overflow - Wildcard in CSS for Classes