响应式布局 @media screen and (min-width: 960px)

@media screen and (min-width: 960px){
.heading,
.container,
.footing{
width: 960px;
}

.left,
.main,
.right{
float: left;
height: 500px;
}

.left,
.right
{
width: 200px;
}
.main{
margin-left: 5px;
margin-right: 5px;
width: 550px;
}
.container{
height: 500px;
}

}

@media screen and (min-width: 600px) and (max-width: 960px){
.heading,
.container,
.footing{
width: 600px;
}

.left,
.main
{
float: left;
height: 400px;
}
.right{
display: none;
}
.left{
width: 160px;
}
.main{
width: 435px;
margin-left: 5px;
}
.container{
height: 400px;
}
}

@media screen and (max-width: 600px){
.heading,
.container,
.footing{
width: 400px;
}

.left,
.right{
width: 400px;
height: 100px;
}
.main{
margin-top: 10px;
width: 400px;
height: 200px;
}
.right{
margin-top: 10px;
}
.container{
height: 420px;
}
}