Hello,

Please move the code:

body .product-subtotal .woocommerce-Price-amount {
	margin-right: 0 !important;
}

body .product-subtotal .wgm-tax {
	display: block;
	width: 100%;
}

from the Global to Mobile in the Theme Settings > Custom CSS.

The problem that occurred in the Firefox on mobile may be caused by increased font size. This font size is increased either by the browser settings or your device settings. We have checked the issue on our devices in Firefox and we do not see the problem: https://prnt.sc/NfMgXZSYC8vC

If you have any questions please feel free to contact us.

Best Regards