.quantity{
   display:flex;
   width:160px;
}

/* it will support chrome and firefox */
.quantity input[type=number]::-webkit-inner-spin-button,
.quantity input[type=number]::-webkit-outer-spin-button{
   -webkit-appearance:none;
}

.quantity input,.quantity button{
   width:50px;
   height: 35px;
   font-size:1.0rem;
   text-align:center;
   font-weight:900;
   background:white;
   border:1px solid #aaa;
}

.quantity input{
   border-left:none;
   border-right:none;
}