/* General styling */
body {
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-color: #f4f4f4;
    margin: 0;
}

/* Calculator styling */
.calculator {
    background-color: #333;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 0 15px rgba(0, 0, 0, 0.3);
    width: 300px;
}

/* Display area */
#display {
    width: 100%;
    height: 50px;
    background-color: #222;
    color: white;
    font-size: 2em;
    text-align: right;
    padding: 10px;
    border: none;
    border-radius: 5px;
    margin-bottom: 20px;
    box-sizing: border-box;
}

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

button {
    background-color: #555;
    color: white;
    border: none;
    padding: 20px;
    font-size: 1.5em;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.2s ease;
}

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

button:active {
    background-color: #444;
}

button.equal {
    grid-column: span 4;
    background-color: #e67e22;
}

button.equal:hover {
    background-color: #d35400;
}

button.equal:active {
    background-color: #c0392b;
}

button:focus {
    outline: none;
}