body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #ffc0cb; /* Thêm màu hồng cho background */
}

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

h1 {
    text-align: center;
}

#result {
    width: 100%;
    box-sizing: border-box;
    padding: 10px;
    font-size: 24px;
    text-align: right;
    border: none;
    background-color: #f0f0f0;
    margin-bottom: 10px;
}

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

button {
    padding: 10px;
    font-size: 18px;
    border: none;
    background-color: #e0e0e0;
    cursor: pointer;
}

.operator {
    background-color: #ffa500;
    color: #fff;
}

.equal {
    background-color: #4caf50;
    color: #fff;
    grid-column: 4 / 5;
    grid-row: 4 / 6;
}