styles.css

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

body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-color: #f5f5f5;
    font-family: 'Arial', sans-serif;
}

.calculator {
    background-color: #fff;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0px 5px 15px rgba(0, 0, 0, 0.2);
    width: 260px;
}

#display {
    width: 100%;
    height: 50px;
    font-size: 24px;
    padding: 10px;
    text-align: right;
    border: none;
    border-bottom: 2px solid #ccc;
    margin-bottom: 20px;
    background-color: #f9f9f9;
}

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

button {
    padding: 20px;
    font-size: 18px;
    border: none;
    background-color: #eee;
    cursor: pointer;
    transition: background-color 0.3s;
    border-radius: 5px;
}

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

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

button:nth-child(16) {
    background-color: #4caf50;
    color: white;
}

button:nth-child(16):hover {
    background-color: #45a049;
}