.center {
    width: 500px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    /* stack textbox above buttons */
    align-items: center;
    gap: 20px;
    /* space between textbox and row of buttons */
}

.row {
    display: flex;
    /* number table + function table side by side */
    justify-content: center;
    gap: 20px;
}

button {
    width: 100px;
    height: 50px;
    border: none;
    background-color: #f0f0f0;
    font-size: 24px;
    cursor: pointer;
}

button:hover {
    background-color: #e0e0e0;
}

.txtOutput {
    width: 100%;
    /* match container width */
    height: 50px;
    border: 1px solid #ccc;
    font-size: 24px;
    text-align: right;
    /* calculator-style text */
    padding: 5px;
}

/* .numerals
{

} */

.function {
    background-color: #f9f9f9;
}

.function:hover {
    background-color: #f0f0f0;
}

.equals {
    width: 200px;
    background-color: #4CAF50;
    color: white;
}

.equals:hover {
    background-color: #45a049;
}