* {
    text-align: center;
    font-family: Georgia serif;
}
header, footer {
    background: tomato;
    color: mistyrose;
    padding: 10px;
}
#nav_block {
    width: 20%;
}
.block {
    background: #FFAEA5;
    height: 170px;
    font-size: 200%;
}
#main_block {
    background: mistyrose;
    width: 80%;
    height: 510px;
    overflow: auto;
}
table {
    margin: auto;
}