Style every third element?

Question

How can I style every third element with plain CSS.

I have seen questions like this, but they involve javascript. I want a plain CSS solution. I know I can use

Answer 1

Possible solution is

section div:nth-child(3n+1) {  
    color: #ccc;
}

The above code styles every 3rd element starting from first element as requested.
Change the number after '+ sign' to set the starting element.
Change the number before n charecter to set the elements after to be styled