背景图片，图片，跑到别的div，页面最下面有空白

body{
padding: 0;
margin:0;
overflow-x:hidden;
}

.name{
position: absolute;
right: 60px;
font-size:50px;
}
.nav li a:link{
color: black;
text-decoration: none;
}
.nav li{

display: inline;
color: black;
position: relative;
left: 350px;
font-size: 22px;
}

#a2{

height: 100px;
background-image: url(images/1.jpg);
}

#a2 h2{
color: white;
font-size: 60px;
margin: 0 auto;
position: relative;
left: 500px;
line-height: 100px;
font-family: "微软雅黑";
}

#a3 h3{
position: relative;
left: 500px;
font-family: "agency fb";
font-size: 50px;
}

#a41{
font-size: 20px;
float: left;
}

#a41 img{
width: 445px;
height: 200px;

}
#a41 p{
width:445px;
font-size: 15px;
text-align: center;
}

#a5{
height: 400px;
background-image:url(images/1.jpg);
}
#a51 {
font-size: 20px;
display: inline;
width: 455px;
color: black;
}
#a6{
position: relative;
top: 60px;
left: 260px;
}
#a61{
float: left;
}
#a61 img{
width: 200px;
height: 330px;

}
#a61 p{
color: black;
font-size: 15px;
text-align: center;
}

.box{

height: ;
position: relative ;
top: 60px;
background-color:gray;
clear: both;
color: white;
height: 300px;
}

span{
position: relative;
left: 200px;
top: 100px;
font-size: 40px;
}

.small{
font-size: 20px;
}
.box li{
line-height:30px ;

}
.box ul{
list-style-type: none;
position: relative;
left: 500px;
}
.box a:link{
color: white;
font-size: 15px;
text-decoration: none;
}

section{
position:relative;
left: 120px;
bottom: 115px;
}
.box p:first-child{
font-size: 30px;
}
.box p{
position: relative;
left: 960px;
bottom: 280px;
}
.one{
font-size:14px;
background-color: black;
color: white;
}
input{
position: relative;
left: 960px;
bottom: 280px;
}
ul{
padding: 0;

http://www.cnblogs.com/Denny_Yang/archive/2011/11/28/2266354.html

定位和浮动冲突了，解决办法，在你的浮动元素外面包一层标签，要设置高，当然也可以不设置高，那就要js处理了，浮动结束注意最好还是清除一下浮动

不用背景图片，直接用《div》《img》