The read more button in your site seems to be not a WPSP read more button anymore.
If thatโs the case, with your current structure, you would need this CSS instead to alter the size and font-size:
p.read-more-button-container a {
padding: 5px 10px;
font-size: 12px;
}
The padding changes the size of the button. The first value is for top and bottom padding, whereas the second value is for left and right padding. Kindly change the values to what suits you best.
Hope this helps! ๐