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

section > div:nth-child(3n+1) {
    background:red;
}

This style is good for fixing your problem, but '>' this symbol, isn't supported for old browsers, for example: IE5, IE6, IE7 . . .

But I prefer this way, without '>' symbol

section div:nth-child(3n+1) {
    background:red;
}