Text Smoothness changing on hover

Question

When I hover the boxes the white text is changing smoothing automatically and getting it fixed automatically as well, not sure why font smoothness is being changed, here is the link

I tried with the following code to fix it, but no effect at all:

<style>
 body
  { 
   -webkit-font-smoothing: antialiased;
    text-rendering: optimizeLegibility;
  }
</style>