* {
  padding: 0px;
  margin: 0px;
}
#grid-container {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: 100px 1fr 100px;
  height: 100vh;
  gap: 5px;
}
#grid-container div {
  padding: 20px;
  background: #CCCCCC;
}
#box-1 {
  grid-column: 1 / span 3;
}
#box-2 {
  grid-column: 1 / span 2;
}
#box-3 {
  grid-column: 3 / 4;
}
#box-4 {
  grid-column: 1 / span 3;
}