Feature box icon bug(?)

Hello Everyone!

As my topic states, I think there is a bug or maybe I have done something wrong with my feature box icons. Please take a look at my start page in the bottom section. https://www.test.opening.se

In Cornerstone all three icons looks good but when I visit my site, the second and third icon is barely visible. It really looks like they have 1px in size or something. The weird part is that my working icon is duplicated in order to create the other two so I do not understand how the two latter looks this way.

I have tried to make a new section with new boxes but nothing works. Would really appreciate if someone could help me with this!