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

body {
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;

    background-color: #f4f4f4;
}

.calculator {
    background-color: #fff;
    border-radius: 10px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);

    width: 300px;
}

#display {
    width: 100%;
    height: 50px;
    text-align: right;
    font-size: 30px;
    padding: 10px;
    margin-bottom: 20px;
    border: 1px solid #ccc;
    border-radius: 5px;
}

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

button {
    background-color: #f0f0f0;
    border: 1px solid #ddd;
    border-radius: 5px;
    font-size: 20px;
    padding: 15px;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

button:hover {
    background-color: #ddd;
}

button:active {
    background-color: #bbb;
}