I have a question about using multiple declarations with one @media query.

/**********************
Responsive css file
***********************/


/***********************************
Below the background will change to
a different color when the browser
window is 480px
************************************/

@media screen and (min-width: 480px) {
  body {
    background: #00CC99;
  }

  header {
    background: #99FFCC;
  }

  .nav {
    background: #9999CC;
  }

  .main-content {
    background: #CC99FF;
  }

  footer {
    background: #99FFCC;
  }

}


/***********************************
Below the background will change to
a different color when the browser
window is 660px
************************************/

@media screen and (min-width: 660px) {
  body {
    background: #009999;
  }

  header {
    background: #CCFFCC;
  }

  .nav {
    background: #99CCCC;
  }

  .main-content {
    background: #CCCCCC;
  }

  footer {
    background: #CCFFCC;
  }

}