css grid must know code example

Example 1: css grid

.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";
}

Example 2: choose grid position html

/* grid-column: <start> / <end>;  */
/* grid-row: <start> / span <length>;  */
/* i.e */
grid-column: 3 / span 2;
grid-row: 2 / 4;
grid-row: 4;