body {
    font-family: 'Courier New', Courier, monospace;
    background-color: #f4f4f4;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}

.calculator {
    width: 220px;
    padding: 20px;
    border: 2px solid #8b4513;
    border-radius: 10px;
    background-color: #f5deb3;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.2);
    text-align: center;
}

.display {
    width: 100%;
    height: 40px;
    margin-bottom: 10px;
    text-align: right;
    font-size: 18px;
    padding: 5px;
    box-sizing: border-box;
    border: 2px solid #8b4513;
    border-radius: 5px;
    background-color: #fff8dc;
    color: #8b4513;
}

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

.button {
    padding: 15px;
    font-size: 18px;
    cursor: pointer;
    border: 2px solid #8b4513;
    border-radius: 5px;
    background-color: #fff8dc;
    color: #8b4513;
    transition: background-color 0.3s;
}

.button:hover {
    background-color: #f5deb3;
}