title: What does this line of CSS mean? @media only screen and (min-device-width: 320px) and (max-device-width: 480px)
body: <p>I found the following line of code inside Wordpress' Twenty Eleven theme stylesheet.</p>
  
  <p>What does it mean?</p>
  
  <pre><code>@media only screen and (min-device-width: 320px) and (max-device-width: 480px)
  </code></pre>