body {
    background: gray;
    font-family: Tahoma, Arial;
    font-size: 12px;
    color: #000;
}

#container {
    width: 960px;
    margin: auto;
    background: #c0c0c0;
    border: 3px solid #808080;
}

header {
    background: linear-gradient(#dcdcdc, #b0b0b0);
    padding: 10px;
    border-bottom: 3px ridge #999;
}

header h1 {
    margin: 0;
}

#content {
    display: flex;
}

nav {
    width: 180px;
    background: #dcdcdc;
    border-right: 3px ridge #999;
    padding: 10px;
}

nav a {
    display: block;
    padding: 6px;
    margin-bottom: 5px;
    background: lightgrey;
    border: 2px outset #999;
    text-decoration: none;
    color: black;
}

nav a:hover {
    background: #ffffff;
}

main {
    flex: 1;
    padding: 15px;
}

aside {
    width: 200px;
    background: #dcdcdc;
    border-left: 3px ridge #999;
}

.panel {
    background: #eeeeee;
    border: 2px inset #999;
    padding: 10px;
}

footer {
    text-align: center;
    padding: 10px;
    background: #b0b0b0;
    border-top: 3px ridge #999;
}