Can You Use Google's Design Content?

Im designing a mybb theme based out of google design . Its just like google taking form of a mybb forum.

Im thinking to use all the sprite icons , button backgrounds , icons of google itself.

Can i use this content similar to the content we use like google images.

Are this copyrighted or free to use?

I can almost guarantee that it is all copyrighted.

All their images will automatically be copyright to Google, so no, you won't be able to use them.