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

.calculator {
    background-color: #333;
    border-radius: 10px;
    padding: 20px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.3);
}

.display {
    margin-bottom: 20px;
}

#result {
    width: 100%;
    height: 60px;
    font-size: 2em;
    text-align: right;
    padding: 10px;
    border: none;
    background-color: #444;
    color: white;
    border-radius: 5px;
}

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

button {
    padding: 20px;
    font-size: 1.2em;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    background-color: #666;
    color: white;
    transition: background-color 0.2s;
}

button:hover {
    background-color: #777;
}

.operator {
    background-color: #ff9500;
}

.operator:hover {
    background-color: #ffaa33;
}

.equals {
    background-color: #2ecc71;
    grid-column: span 2;
}

.equals:hover {
    background-color: #27ae60;
}