css & htmll footer

body{
background-image:url(images/1777.png);
}
 
 
 ul {
list-style: none;
}
 
 
#header{
height:205px;
width:920px;
border:2px solid #48A1E5;
margin:5px auto;
background-image:url(images/nkar.jpg);
 
}
 
#sidebarR {
float:right;
background-color:#e5e5e5;
background-image:url(images/bodybg.jpg);
background-repeat:repeat-x;
margin-right:370px;
margin-top:5px;
width:195px;
border:1px solid #000000;
 
}
 
#content{
background-color:#e5e5e5;
background-image:url(images/bodybg.jpg);
background-repeat:repeat-x;
width:720px;
margin:5px 160px 12px 371px;
border:1px solid #000000;
}
 
 
 
 
#logo {
text-align:center;
padding:70px;
font-size:35px;
font-family:Arial;
color:#3C70FF;
}
 
 
 
#nav{
width:960px;
height:55px;
outline:0px solid #B1C1E2;
margin:0 auto;
 
}
 
 
#nav li {
float:left;
outline:0px solid #B1C1E2;
height:55px;
width:184px;
text-align:center;
background-color:#31ADE2;
}
 
 
#nav li a {
outline:1px solid #B1C1E2;
display:block;
height:40px;
padding-top:15px;
font:17px Aria,sans-serif;
color:#ffffff;
text-decoration:none;
background-repeat:no-repeat;
background-position:0 -55px;
}
 
a:hover{
background-color:#8CD5FE;
}

#footer {
height: 100px;
width: 100%;
border: 1px solid #48A1E5;
margin: 5px auto;
background: green;
}

#footer {
height: 100px;
width:720px;
border: 1px solid #48A1E5;
margin: 5px auto;
background: green;
}

#footer {
height: 100px;
width:920px;
border: 1px solid #48A1E5;
margin: 0 auto;
background: gray;
}

#footer {
height: 100px;
width:920px;
margin: 0 auto;
background: gray;
}

#footer {
    width: 900px;
    height: 40px;
    margin-left: auto;
    margin-right: auto;
    bottom: 0;
    background-color: #000;
    border: 1px solid #FF0;
}

bottom: 0px !important;