grid.css

.item-a { 
  grid-area: header;
} 
.item-b { 
  grid-area: main;
} 
.item-c { 
  grid-area: sidebar;
} 
.item-d { 
  grid-area: footer;
} 
.container { 
  display: grid;
  grid-template-columns: 50px 50px 50px 50px;
  grid-template-rows: auto;
  grid-template-areas: "header header header header" "main main . sidebar" "footer footer footer footer"; 
}