title: How to color only two divs of the same class or ID?
body: <p>My site is divided in blocks, and each left blocks have class block_1 and on the right part of the page have block_2.</p>
  <p>How can I change only first div with block_1 class? .block1:nth-child(1){background-color:red;} works, but at all divs with block_1 class</p>