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

        body {
            min-height: 100vh;
            background: black;
            display: flex;
            justify-content: center;
            align-items: center;
            font-family: 'SF Pro Display', -apple-system, BlinkMacSystemFont, sans-serif;
            position: relative;
        }

        .calculator {
            background: rgba(255, 255, 255, 0.15);
            backdrop-filter: blur(20px);
            border-radius: 25px;
            border: 1px solid rgba(255, 255, 255, 0.2);
            padding: 30px;
            box-shadow: 0 25px 50px rgba(0, 0, 0, 0.3);
            width: 350px;
            position: relative;
        }

        .display {
            background: rgba(0, 0, 0, 0.3);
            border-radius: 15px;
            padding: 25px 20px;
            margin-bottom: 25px;
            border: 1px solid rgba(255, 255, 255, 0.1);
        }

        .current-operand {
            color: white;
            font-size: 3rem;
            font-weight: 400;
            text-align: right;
            min-height: 50px;
            word-wrap: break-word;
            word-break: break-all;
            text-shadow: 0 0px 10px rgba(0, 0, 0, 0.3);
        }

        .previous-operand {
            color: rgba(255, 255, 255, 0.6);
            font-size: 1.2rem;
            text-align: right;
            min-height: 20px;
            margin-bottom: 5px;
        }

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

        .btn {
            background: black;
            border: 1px solid rgba(255, 255, 255, 0.2);
            border-radius: 15px;
            color:yellow;
            font-size: 1.3rem;
            font-weight: 500;
            padding: 20px;
            cursor: pointer;
            transition: all 0.2s ease;
            backdrop-filter: blur(10px);
        }

        .btn:hover {
            background:yellow;
            color:black;
            transform: translateY(-1px);
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
        }

        .btn:active {
            transform: translateY(0);
        }

        .btn.operator {
            background: black;
            color: yellow;
            font-weight: 600;
        }

        .btn.operator:hover {
            background: red;
            color:black;
        }

        .btn.equals {
            background: black;
            color: white;
            font-weight: 600;
        }

        .btn.equals:hover {
            background: linear-gradient(135deg, #c31fdc, #00695c);
        }

        .btn.clear {
            background: black;
            color: white;
            font-weight: 600;
        }

        .btn.clear:hover {
            background: linear-gradient(135deg, #ff9800, #f57c00);
        }

        .btn.span-two {
            grid-column: span 2;
        }

        /* Subtle outer glow */
        .calculator::after {
            content: '';
            position: absolute;
            top: -2px;
            left: -2px;
            right: -2px;
            bottom: -2px;
            background: linear-gradient(45deg, #ff6b6b, #4ecdc4, #45b7d1, #96ceb4);
            border-radius: 27px;
            z-index: -1;
            filter: blur(8px);
            opacity: 0.3;
        }