google speed

Hi there, I use your nice plugin and I load in the head section css and js.

I’m using w3 cache to optimize my website but I have problem with

http://www.corradoprever.com/wp/wp-admin/admin-ajax.php?action=slideshow_jquery_image_gallery_load_stylesheet&style=style-light&ver=2.2.21

http://www.corradoprever.com/wp/wp-admin/admin-ajax.php?action=slideshow_jquery_image_gallery_load_stylesheet&style=style-dark&ver=2.2.21

I got error from w3 cache if I try to minify those css and add together with others css to perform better in Google speed.

If I load js and css in footer no problem about Google speed but can not validate w3c.

How can solve the issue?

https://ww.wp.xz.cn/plugins/slideshow-jquery-image-gallery/