Zebra stripe every two TRs in a row with CSS.

Question

I want to grey/stripe every two rows in a row. Its hard to explain. Here's a picture::
|-^-^-^-^-^-|
|-^-^-^-^-^-|
|-------------|
|-------------|
|-^-^-^-^-^-|
|-^-^-^-^-^-|
|-------------|
|-------------|
|-^-^-^-^-^-|
|-^-^-^-^-^-|
|-------------|
|-------------|

Answer 1

Like this? http://jsfiddle.net/GQNUV/1/

table tr:nth-child(4n-1), table tr:nth-child(4n)  {
    background: #ccc;
}

Answer 2

Change this to your preference, it should work

tr:nth-child(4n+1) { color: green; }
tr:nth-child(4n+2) { color: green; }
tr:nth-child(4n+3) { color: red; }
tr:nth-child(4n+4) { color: red; }