* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 50%, #f093fb 100%);
            min-height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
            padding: 20px;
        }

        .calculator {
            background: rgba(255, 255, 255, 0.25);
            backdrop-filter: blur(15px);
            border-radius: 25px;
            padding: 35px;
            box-shadow: 0 15px 45px rgba(0, 0, 0, 0.2), 
                        0 5px 15px rgba(0, 0, 0, 0.1),
                        inset 0 1px 0 rgba(255, 255, 255, 0.3);
            border: 1px solid rgba(255, 255, 255, 0.3);
            max-width: 400px;
            width: 100%;
        }

        .display {
            background: rgba(255, 255, 255, 0.3);
            border-radius: 20px;
            padding: 25px;
            margin-bottom: 25px;
            text-align: right;
            min-height: 80px;
            display: flex;
            flex-direction: column;
            justify-content: center;
            border: 1px solid rgba(255, 255, 255, 0.4);
            box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.1);
        }

        .display-main {
            color: #2d3748;
            font-size: 2.5rem;
            font-weight: 300;
            min-height: 40px;
            overflow: hidden;
            word-break: break-all;
            text-shadow: 0 1px 2px rgba(255, 255, 255, 0.5);
        }

        .display-previous {
            color: #4a5568;
            font-size: 1rem;
            margin-bottom: 5px;
            min-height: 20px;
        }

        .buttons {
            display: grid;
            grid-template-columns: repeat(4, 1fr);
            gap: 15px;
        }

        button {
            background: rgba(255, 255, 255, 0.4);
            border: none;
            border-radius: 18px;
            color: #2d3748;
            font-size: 1.2rem;
            font-weight: 600;
            height: 65px;
            cursor: pointer;
            transition: all 0.3s ease;
            backdrop-filter: blur(10px);
            border: 1px solid rgba(255, 255, 255, 0.5);
            box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1),
                        inset 0 1px 0 rgba(255, 255, 255, 0.6);
            text-shadow: 0 1px 2px rgba(255, 255, 255, 0.8);
        }

        button:hover {
            background: rgba(255, 255, 255, 0.6);
            transform: translateY(-3px);
            box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15),
                        inset 0 1px 0 rgba(255, 255, 255, 0.8);
        }

        button:active {
            transform: translateY(0);
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
        }

        .operator {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            text-shadow: 0 1px 2px rgba(0, 0, 0, 0.3);
        }

        .operator:hover {
            background: linear-gradient(135deg, #5a67d8 0%, #6b46c1 100%);
            box-shadow: 0 8px 25px rgba(102, 126, 234, 0.4),
                        inset 0 1px 0 rgba(255, 255, 255, 0.3);
        }

        .equals {
            background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
            color: white;
            text-shadow: 0 1px 2px rgba(0, 0, 0, 0.3);
        }

        .equals:hover {
            background: linear-gradient(135deg, #ed64a6 0%, #f56565 100%);
            box-shadow: 0 8px 25px rgba(240, 147, 251, 0.4),
                        inset 0 1px 0 rgba(255, 255, 255, 0.3);
        }

        .clear {
            background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
            color: white;
            text-shadow: 0 1px 2px rgba(0, 0, 0, 0.3);
        }

        .clear:hover {
            background: linear-gradient(135deg, #3182ce 0%, #00b4d8 100%);
            box-shadow: 0 8px 25px rgba(79, 172, 254, 0.4),
                        inset 0 1px 0 rgba(255, 255, 255, 0.3);
        }

        .zero {
            grid-column: span 2;
        }

        @media (max-width: 480px) {
            .calculator {
                padding: 20px;
            }
            
            .display-main {
                font-size: 2rem;
            }
            
            button {
                height: 50px;
                font-size: 1rem;
            }
        }