The world is fucked up – Only Screenshots taken on a mac is considered “Professional”.
If you use one of the other operating systems use this tool to showcase your website like it is running on safari on a mac. Plus even if you have osx, you can use this to generate a full-length-safari-window screenshot (without scrollbars).
Works best on firefox. File apis does not work on safari. Style your buttons and input elements. For a demo, skip everything and click “show my screenshot”.