I am trying to hide the first 3 elements having the class .row inside the block .container.
What I\'m doing is hiding all the .row
You have a .notarow as the first child, so you have to account for that in your :nth-child() formula. Because of that .notarow, your first .row becomes the second child overall of the parent, so you have to count starting from the second to the fourth:
.row:nth-child(-n+4){
display:block;
}
Updated fiddle
What you're doing is fine.