!important on any utility or single responsibility class. They are not meant to be overridden — meaning, if you need to override them you shouldn't use them in the first place. Your custom CSS should not include
!important unless you are extending the Solid system and creating similar single responsibility classes.
A custom class is attempting to override a Solid class by using three margins but changing the fourth.
Custom classes are welcome, so long as they are not competing with or attempting to override Solid's utility classes.
Extending the system, this custom class bears one and only one responsibility, and therefore can use