body{font-family:Arial,sans-serif;display:flex;justify-content:center;align-items:center;height:100vh;margin:0;background-color:#f4f4f9}h1{text-align:center;margin-bottom:20px}.display{margin:10px auto;padding:10px;font-size:1.5rem;font-weight:700;background-color:beige;border:2px solid #333;border-radius:8px;width:300px;height:50px;text-align:right;box-shadow:2px 2px 5px #0000001a}.button-container{text-align:center}button{width:60px;height:60px;margin:5px;font-size:1.2rem;font-weight:700;border:none;border-radius:5px;cursor:pointer;transition:background-color .3s ease,transform .2s ease}button.number{background-color:#007bff;color:#fff}button.operator{background-color:#ff5722;color:#fff}button.operator.equal{background-color:#4caf50}button:hover{opacity:.9}button:active{transform:scale(.95)}