jQuery UI button with smoothness theme grows when clicked and held
Remove
button:activefrom
button:active, input[type="submit"]:active, input[type="button"]:active, input[type="reset"]:active { background: #d94412; background: -webkit-linear-gradient(top, #d94412 0%, #e05d22 100%); background: linear-gradient(to bottom, #d94412 0%, #e05d22 100%); border: none; border-top: 3px solid #b93207; padding: 10px 24px 11px;}Or just set it's padding to 0.
button:active{ padding: 0;}This will prevent it from expanding on being active (click).
One way to see the element states is by inspecting in chrome and using inspector tools:
Or use the fact that those buttons have their ID's so
button#nextGame:active,button#prevGame:active{ padding:0;}