Custom CSS does not overide the plugin?

Hi,

I’m trying to customize the thumbnails generated by Yaarp. The page in question is here:
https://www.finerthingsbuyer.com/the-best-travel-gear-and-accessories-of-2022/

I wanted to remove the border and change the spacing a bit, but it seems no CSS has taken effect. I tried the same exact CSS here on another site which worked:
.yarpp-thumbnails-horizontal .yarpp-thumbnail {border:none;}

Just trying to remove the borders first.

Though this time the thumbnails are showing in the sidebar. I also tried disabling the style sheets as shown here, thinking only my own CSS would take effect:
https://ww.wp.xz.cn/support/topic/disable-yarpp-stylesheet/

Still no good unfortunately.

The page I need help with: [log in to see the link]