.startblock {
    margin-top: 100px;    
    width: 800px;
    height: 500px;
    margin-left:auto;
    margin-right:auto;
}
.startblockcenter {
    margin: auto;
    //width: 60%;
    padding:10px;
}
IMG.startblockcenter {
    display: block;
    margin-left: auto;
    margin-right: auto;    
}
p.startblockcenter {
    font-size: 20px;
    font-family: sans-serif;
    text-align: center;
}