.calculator{width:400px;margin:0 auto;text-align:center;padding:20px;box-shadow:0 0 10px rgba(0,0,0,.2);border-radius:5px}.calculator .display input{width:80%;font-size:24px;padding:10px;margin:10px;text-align:center}.calculator .buttons button{width:20%;padding:15px;margin:5px;font-size:18px}.buttons button:hover{background-color:lightgray}