Centering Mashshare Buttons

Add the code below in Mashshare Settings->Customisation->Custom Styles


.mashsb-container {
    margin: 0 auto;
    max-width: 660px;
 }

Adjust max-width to the estimated total width of all your visible Buttons which are in one line incl. share count.
The higher the value the more the buttons align to the left. Try out which value is the best for your site.