Header Nav Menu and E-mail Share

We would like to know two things in the process of developing our website:
1) We really like the way in which we had the header appears transparent on our old website https://brandtheglobe.com/ and then turns completely dark gray. Furthermore, the text in the navigation menu in the header starts with one color at the top and changes when the users scroll down and the dark background appears. Is there a way to do this header color effect for the text on the current website? I have achieved the background effect by setting the opacity to zero but I cannot figure out the changing color of the text.
2) Is it possible to give users the options to share some pages via e-mail? I know that there is a social share bar in the Visual Composer widgets but I would like to have the one that deals exclusively with sharing via e-mail.

Thank you and have a good evening!