Grid Layout Demo

grid-template: correct number of grid-area (columns) for each row
column width:fractional spacing optional use /
height: auto / 100px optional

#wrapper {
display: grid;
grid-gap: 5px;
grid-template:
  "h h h" 100px
  "l m r" auto
  ". f ."
  / 150px 3fr 1fr;"
}

header {
  grid-area: h;
  border: solid red;
}

#grid_l {
  grid-area: l;
  border: solid blue;
}

#grid_m {
  grid-area: m;
  border: solid orange;
  overflow: auto;
  height: 130px;
}