body {
    font-family: 'Roboto', sans-serif;
    background-color: #f0f0f0;
    margin: 0;
    padding: 20px;
}

h1 {
    text-align: center;
    color: #333;
}

.calculator-container {
    max-width: 300px;
    margin: 0 auto;
    background-color: #fff;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

#display {
    width: 100%;
    padding: 15px;
    font-size: 24px;
    text-align: right;
    border: 1px solid #ccc;
    border-radius: 4px;
    box-sizing: border-box;
}

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

button {
    padding: 20px;
    font-size: 18px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.3s;
}

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

#equals {
    background-color: #4CAF50;
    color: white;
}

#clear {
    background-color: #f44336;
    color: white;
}