div {
  padding: 20px;
  margin: 5px; 
  float: left;
}

#all {
  width: 93%;
  background-color: lightgray;
}

#box1 {
  background-color: powderblue;
  width: 2.6rem
}

#box2 {
  background-color: lightcyan;
  width: 2.6rem
}

#box3 {
  background-color: lime;
  width: 2.6rem
}