header {
    text-align: center;
    border: 1px solid;
    border-radius: 10px;
    width:1000px;
    margin-bottom: 15px;
}
footer {
    text-align: center;
    border: 1px solid;
    border-radius: 10px;
    clear:both;
    margin-top: 15px;
    width:1000px;
}

aside {
    width: 15%;
    float: left;
    margin-bottom: 10px;
    margin-top: 10px;
}

nav {
    clear: both;
    padding-top: 15px;
}

main {
    float: left;
    border: 1px solid red;
    width: 800px;
    text-align: center;
}

/* Text/Content */
h1, h2, h3 {
    text-align: center;
}

p{
    text-align: left;
    margin-top: 5%;
    margin-left: 10%;
    margin-right: 10%;
}
img {
    width:400px;
}
fieldset {
    width: 10%;
    float: left;
}
#chessimg {
    text-align: center;
}

section {
    width: 100%;
    text-align: center;
    margin: 10px auto;
    float: left;

}

/* Tabelle */
table {
    border-collapse: collapse;
    margin-left:auto;
    margin-right:auto;
    margin-bottom: 20px;
}
table, th, td {
    border: 1px solid black;
}
.guestbook{
    width: 100%;
    margin-left:auto;
    margin-right:auto;

}

.guestbook table, .guestbook th, .guestbook td {
    border: 0px solid black;
    text-align: left;
}