style.css

.calculator {
    width: 300px;
    margin: 50px auto;
    background-color: #333;
    border-radius: 10px;
    overflow: hidden;
}

.calculator input {
    width: 100%;
    padding: 20px;
    font-size: 24px;
    border: none;
    background-color: #222;
    color: white;
    text-align: right;
}

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

.calculator button {
    padding: 20px;
    font-size: 20px;
    border: none;
    background-color: #444;
    color: white;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.calculator button:hover {
    background-color: #555;
}

.calculator button:active {
    background-color: #666;
}

.calculator .buttons button:nth-child(4n) {
    background-color: #f0a040;
}

.calculator .buttons button:nth-child(4n):hover {
    background-color: #f2b96e;
}