body {
    background-color: #f5f5f5;
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

.calculator {
    background-color: #fff;
    border-radius: 8px;
    box-shadow: 0px 2px 10px rgba(0, 0, 0, 0.1);
    padding: 20px;
    width: 300px;
}

.calculator-grid {
    display: grid;
    gap: 10px;
    grid-template-columns: repeat(4, 1fr);
}

.calculator-grid button {
    background-color: #e0e0e0;
    border: none;
    border-radius: 4px;
    color: #333;
    cursor: pointer;
    font-size: 18px;
    padding: 10px;
    text-align: center;
    transition: background-color 0.3s ease;
}

.calculator-grid button:hover {
    background-color: #ccc;
}

.calculator-grid button.ac {
    background-color: #f44336;
    color: #fff;
}

.calculator-screen {
    background-color: #f5f5f5;
    border: 1px solid #ccc;
    border-radius: 4px;
    font-size: 24px;
    padding: 10px;
    text-align: right;
    width: 100%;
}