Hello @MAHDAR,
We suggest that you copy and paste the following CSS code into XStore >> Theme Options >> Theme Custom CSS >> Global CSS. After doing so, please clear your browser cache and check back to your site. This should resolve your issue.
.etheme-sticky-cart form.variations_form .single_add_to_cart_button.button {
margin: 15px 0 0 0;
}
Best Regards,
8Theme’s Team