样式列表class 与id的区别

#footer{
clear:both;
color:#806a4f;
height:102px;
width:1024px;
margin:0 auto;
background:url(imgs/footer.jpg) top left no-repeat;
}
#footerleft{
margin:0 27px 0 0;
width:720px;
float:left;
}
#footerleft ul{
height:20px;
width:100%;
margin:0;
padding:20px 0 0 150px;
}
#footerleft ul li{
float:left;
margin:0;
padding:0;
}
#footerleft ul li a{
display:block;
margin:0 5px 0 0;
float:left;

}
#footerleft p{
margin:0 0 0 150px;
text-align:left;
}
#footerright{
margin:15px 0 0 0;
float:left;
height:23px;
width:176px;
background:url(imgs/searchback.gif) no-repeat top left;
border:1px solid #cdc59c;
}

.footer{ width:176px;}