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

body {
    font-family: Arial, sans-serif;
    background-color: #f4f4f4;
    color: #333;
}

.calculator {
    width: 300px;
    margin: 50px auto;
    padding: 20px;
    border: 1px solid #ccc;
    border-radius: 5px;
    background-color: #fff;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

#display {
    width: 100%;
    height: 40px;
    margin-bottom: 10px;
    padding: 5px;
    font-size: 1.5rem;
    border: 1px solid #ccc;
    border-radius: 5px;
    text-align: right;
}

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

button {
    padding: 10px;
    font-size: 1.5rem;
    border: none;
    border-radius: 5px;
    background-color: #f4f4f4;
    cursor: pointer;
    transition: background-color 0.3s;
}

.dot {
    font-weight: bold;
    font-size: 2rem;
}

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

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