body{
    margin: 0px 10px 0px 10px;
    padding: 0px;
}
#app{
    display: grid;
    grid-template-areas: "app_header"
                         "app_body"
                         "app_footer";
}
.app_header{
    grid-area: app_header;
}
.app_body{
    display: grid;
    grid-area: app_body;
    grid-template-columns: 10% 80% 10%;
    grid-template-areas: "left_col  shelf  right_col"
}
.app_footer{
    grid-area: app_footer;
}
.left_col{
    grid-area: left_col
}
.shelf{
    grid-area: shelf
}
.right_col{
    grid-area: right_col
}