Hello @ash,
This is the default color behavior of the “Add to Cart” button on the single product page. If the product is a simple product, the button color will be sharp. If the product is a variable product, the button color will be slightly dim, as an indication for the customer to choose the variations first. Once the variation is chosen, the button color will become sharp. Please refer to the following screenshots for reference:
Simple Product: https://postimg.cc/Fk4FBKX1
Variable Product: https://postimg.cc/0618QQrn https://postimg.cc/pyh10Bs9
Best Regards,
8Theme’s Team