Responsive Web Design

The template of CSS

<style>
  /* For mobile phones: */
  .content{
  }
  /* For tablets: */
  @media only screen and (min-width: 600px) {
    .content{
    }
  }
  /* For desktop: */
  @media only screen and (min-width: 768px) {
    .content{
    }
  }
</style>