Sass, Flex-box. Used JavaScript for the share button.

Had a time with the share feature. When it came to mobile responsive size I gave the share button a z-index so it would show above resized share container when it was at the bottom of the screen and adjusted the other elements to line up with it. Wanted to know how others went about it? Also how could I add to my js code to have the share bubble close when clicking anywhere outside of it instead of clicking the share button again to close the share bubble?