css响应式布局

@media screen and (min-width:600px) {
  nav {
    float: left;
    width: 25%;
  }
  section {
    margin-left: 25%;
  }
}
@media screen and (max-width:599px) {
  nav li {
    display: inline;
  }
}

@media only screen and (min-width: 992px) and (max-width: 1199px) {   
　nav li {
    display: inline;
  }
}