.normalbox{
  width: 500px;
  margin: auto;
  border: 5px solid blue;
  padding: 5px;
}

.maxbox{
  max-width: 500px;
  margin: 10px auto;
  border: 5px solid green;
  padding: 5px;  
}

.smallbox{
   width: 500px;
   margin: 50px auto;
   border: 5px solid purple;
}
.bigbox{
   width: 500px;
   margin: 50px auto;
   padding: 50px;
   border: 20px solid pink;
  
}