.calculator{width:320px;margin:50px auto;background:#1e1e1e;padding:20px;border-radius:12px;box-shadow:0 5px 15px #0006}.value{width:300px;height:50px;background:#000;color:#0f0;font-size:1.5rem;text-align:right;padding:10px;border:none;border-radius:6px;margin-bottom:15px;margin-right:15px}.buttons{display:grid;grid-template-columns:repeat(4,1fr);gap:10px}.buttons span{display:flex;justify-content:center;align-items:center;background:#333;color:#fff;font-size:1.1rem;padding:15px;border-radius:8px;cursor:pointer;transition:background .2s ease;-webkit-user-select:none;user-select:none}.buttons span:hover{background:#444}.clear{background:#ff4d4d!important}.clear:hover{background:#e60000!important}.buttons span:last-child{background:#4caf50!important}.buttons span:last-child:hover{background:#3e8e41!important}