body {
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background-color: #f0f0f0;
}

.calculator {
    background: #fff;
    border-radius: 10px;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.2);
    width: 300px;
    padding: 20px;
}

.display {
    margin-bottom: 20px;
}

#result {
    width: 100%;
    height: 50px;
    font-size: 1.5rem;
    text-align: right;
    border: none;
    border-bottom: 2px solid #ddd;
    outline: none;
}

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

button {
    height: 50px;
    font-size: 1.2rem;
    border: none;
    border-radius: 5px;
    background-color: #f9f9f9;
    cursor: pointer;
    transition: background-color 0.2s;
}

button:hover {
    background-color: #e0e0e0;
}

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