body {
  background-image: url("background-image.jpg");
  ​background-attachment: fixed;
}

#web {
    margin-top: 50px;
    background-color: rgb(245, 245, 245);
    width: 1200px;
    height: auto;
    margin-left: auto;
    margin-right: auto;
    padding: 50px;
    border: 3px solid rgb(100, 172, 58);
    border-radius:5px;
    border-top-left-radius: 100px 50px;
    border-bottom-right-radius: 100px 50px;
}
span.warning {
    color: rgb(255, 0, 0);
}
p,a {
    color: rgb(0, 0, 0);
}