body {
            font-family: 'Poppins', sans-serif;
            background-color: #ffffff;
            display: flex;
            justify-content: center;
            align-items: center;
            min-height: 90vh;
        }

        .calculator {
            width: 100%;
            max-width: 350px;
            box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
            border-radius: 60px;
            padding: 20px;
            background-color: #000000;
        }

        .text h1 {
            font-family: 'Poppins', sans-serif;
            text-align: center;
            margin-top: 0;
            margin-bottom: 0.5rem;
            font-size: 1.8rem;
        }

        .display {
            width: 100%;
            height: 70px;
            background-color: #000000;
            border-style: none;
            text-align: right;
            padding: 0 20px;
            font-size: 2.5rem;
            font-family: 'Poppins', sans-serif;
            font-weight: 500;
            color: #000000;
            box-sizing: border-box; 
            margin-bottom: 1.5rem;
            pointer-events: none; 
            color: white;
        }

        .button-rows {
            display: flex;
            flex-direction: column;
            gap: 0.5rem; 
        }
        
        .button-row {
            display: flex;
            justify-content: center;
            gap: 0.5rem; 
        }

        .button-row button {
            height: 75px;
            width: 75px;
            margin: 0; 
            border-radius: 100%;
            border-style: none;
            background-color: rgb(51, 51, 51);
            font-size: 1.3rem;
            font-family: 'Poppins', sans-serif;
            color: white;
            font-weight: 500;
            cursor: pointer;
            transition: background-color 0.2s;
        }

        .button-row button:hover {
            background-color: #d1d1d1;
        }

        .button-row button.operator {
            background-color: rgb(252, 163, 38);
            color: white;
            font-size: 1.5rem;
        }
        .button-row button.operator:hover {
            background-color: #e09122;
        }
        
        .button-row button.utility {
             background-color: #b0b0b0;
             color: rgb(0, 0, 0);
        }
         .button-row button.utility:hover {
             background-color: #a0a0a0;
        }

        .button-row button.zero {
            width: 158px; 
            border-radius: 40px;
        }