* {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}
body {
    background-image: url(../images/background.jpg);
    background-attachment: fixed;
}
div#wrapper {
    width: 980px;
    padding: 20px;
    margin: 20px auto 20px auto;
    overflow: hidden;
}
header {
    overflow: hidden;
}
nav {
    height: 50px;
    line-height: 50px;
    width: 100%;
}
nav ul {
    list-style-type: none;
    width: 940px;
}
nav li{
    float: left;
    width: 50%;
    text-align: center;
}
aside {
    width: 340px;
    float: right;
}
main {
    float: left;
    width: 580px;
}
img.right_align {
    float: right;
    width: 300px;
    margin-left: 20px;
}
img.left_align {
    float: left;
    width: 300px;
    margin-right: 20px;
}
.center {
    margin: 20px auto;
    display: block;
    text-align: center;
    max-width: 100%;
}
footer {
    height: 50px;
    line-height: 50px;
    clear:both;
}
footer li {
    list-style-type: none;
    float: left;
    margin-right: 30px;
}