.container {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr 1fr ;
    grid-auto-rows: minmax(100px, auto);
    grid-template-areas: 
      "hd hd hd .."
      "sd bd bd .."
      "sd ft ft ft";
    gap: 20px;
}

.container :nth-child(1) {
  grid-row: hd-start / bd-end;
  grid-column: sd-end / bd-end;
  background-color: white;
  z-index: 1;
}


.container :nth-child(2) {
  grid-area: sd;
}

.container :nth-child(3) {
  grid-area: bd;
}

.container :nth-child(4) {
  grid-area: ft;
}

.item {
    padding: 10px;
    border: 5px solid rgb(17, 105, 121);
    background-color: rgba(17, 105, 121,.1);
    border-radius: 5px;
}

* { box-sizing: border-box; }

body {
    font: 1.1em/1.3 Tahoma, Verdana, Segoe, sans-serif;
    background-color: #fff;
    color: #333;
    max-width: 960px;
    margin: 1em auto;
}