Hello,
Please try using the below Custom CSS code and paste it to Dashboard >> Theme Settings >> Custom CSS >> Global CSS section.
If you want to change the Hover Color of the Add to Cart button for main Single Product page then please try the following one:
.single_add_to_cart_button:hover {
background: pink !important;
}
If you want to change the Hover Color of the Add to Cart button for Similar Products at the bottom of the Single Product page then please try the following one:
.wd-hover-quick .wd-add-btn>a:hover {
background-color: pink !important;
}
Hope this helps !
Best Regards