header {
background-color: #cc9999;
width: 100%;
height: 100px;
margin-top:20px;
}
nav {
background-color: #ff9999;
width: 100%;
height: 50px;
}
li {
margin-left:30px;
float: left;
}

section {
background-color: #99ff99;
float:left;

width:65%;
height: 1000px;
margin-right:auto;
}
article {
background-color: #ffff99;
width: 90%;
height: 950px;
margin-top:20px;
margin-right:auto;
margin-left:auto;
line-height:25px;
}
aside{
background-color: #cc99ff;
float:right;

width: 35%;
height: 1000px;
line-height:25px;
}
footer{
background-color: #99ffcc;
float:left;

width: 100%;
height: 100px;
}