html,body{
  width: 99%;
  height: 99%;
  background-color: #D5EAFF;
  padding: 0%;
  margin: auto;
  text-align: center;
display: flex;
justify-content: center;
align-items: center;
}
#app{
  width: 100%;
  height: 100%;
  background-color: bule;
}
#divHead,#left,#main,.shelf{
  box-shadow: 0 2px 4px rgba(0, 0, 0, .12), 0 0 6px rgba(0, 0, 0, .04);
}
input::-webkit-outer-spin-button,
input::-webkit-inner-spin-button { 
    -webkit-appearance: none; 
}
*{
  text-align: center;
}