1.) you cannot use big border on parent -- in case you want to have a specific border
2.) you cannot add margin -- in case your parent is a part of some other container and you want your parent to take the full width of that grand parent.
The Only Solution that should be applicable is to wrap your children's in an another container so that your parent becomes the grandparent and then apply padding to the new children's Wrapper / Parent. Or you can directly apply padding to the children.
In your case:
.css-sux{
padding: 0px 10px 10px 10px;
}