Positioning Header-Video and Header Image on mobile?

Hey Guys Setting up Euphony. Thanks for your great work. I have a Header-Video and Image defined (Video is a Youtube-Link) and activated your Header-Enhancement Plugin. Works fine for Desktops, but on Mobile i would like to Position/Fill the gaps (Video and Image are landscape, Mobile is Portrait. How can Video be css'ed so that the whole height is used, positioned left and cutting off the right side of the video? (at the moment it fits to the with resulting in black gaps on top and bottom). Same for the Image (this one fills nicely, but showing a random peace of the image. I d like to see the top left corner of the image). https://www.skinnyjimtennessee.ch Thanks! Daniel