.real-calculator {width: 320px;margin: 40px auto;padding: 20px;background: #e0e0e0;border-radius: 20px;box-shadow: 0 10px 20px rgba(0,0,0,.15);font-family: "Segoe UI",sans-serif;}
#display {width: 100%;height: 50px;font-size: 1.8rem;padding: 10px;margin-bottom: 15px;text-align: right;border: none;border-radius: 10px;background: #fff;box-shadow: inset 0 2px 5px rgba(0,0,0,.1);}
.buttons {display: grid;grid-template-columns: repeat(4,1fr);gap: 10px;}
.btn {padding: 18px;font-size: 1.2rem;border: none;border-radius: 10px;color: white;cursor: pointer;transition: all .2s ease;}
.btn:hover {opacity: .9;transform: scale(1.05);}
.gray {background: #9e9e9e;}
.dark {background: #424242;}
.orange {background: #f57c00;}
.green {background: #43a047;grid-column: span 2;}
.zero {}