body { 
  font-family: 'Helvetica';
  text-align: center; 
}

.main-box{ 
  display: flex;
  flex-wrap: wrap;
}
.one, .two, .three, .four { 
  flex-basis: 40%;
}
kbd {
  text-align: left; 
  display:inline-block;
  line-height:1.5;
}

div { 
  border: 1px lightgrey dotted;
  margin: 30px;
}