Hello @devine721,
To center the thumbnails of the image gallery on the mobile version, please try using the following CSS code in XStore >> Theme Settings >> Theme Custom CSS >> Global CSS, and then clear the browser cache to view the changes.
@media(max-width: 767px){
.single-product .et_product-block.etheme-woocommerce-product-gallery .swiper-container.slider .swiper-wrapper.thumbnails-list.thumbnails {
justify-content: center !important;
}
}
And to make them sharp color, you should use the below given CSS code.
.single-product .swiper-container.swiper-control-bottom.second-initialized li.thumbnail-item {
opacity: 1 !important;
}
Best Regards,
8Theme’s Team