body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background-color: #f2f2f2;
    font-family: Arial, sans-serif;
}

.calculator {
    width: 300px;
    padding: 20px;
    background-color: #222;
    border-radius: 15px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.3);
}

#display {
    width: 100%;
    height: 65px;
    margin-bottom: 15px;
    padding: 10px;
    font-size: 30px;
    text-align: right;
    box-sizing: border-box;
    border: none;
    border-radius: 8px;
    background-color: #fff;
}

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

button {
    height: 60px;
    font-size: 20px;
    font-weight: bold;
    cursor: pointer;
    border: none;
    border-radius: 8px;
    background-color: #eee;
}

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

button:active {
    transform: scale(0.95);
}

button:nth-child(1) {
    background-color: #ff6b6b;
    color: white;
}

button:nth-child(2),
button:nth-child(3),
button:nth-child(4),
button:nth-child(8) {
    background-color: #ffa94d;
    color: white;
}

button:nth-child(12) {
    background-color: #51cf66;
    color: white;
}

button:nth-child(17) {
    grid-column: span 4;
}