Thanks for reaching out, @lzgc. Just to clarify, are you looking to use this custom theme across your app or just within the context of your custom component? I ask because custom components are rendered within their own iframe and, thus, don't inherit any styling rules from its parent.
It's definitely possible to style those custom components in isolation, though. You can look here for one such example. I'm not familiar with Vuexy, in particular, but am happy to help with the implementation if you're able to share a little more detail!