I see your UX developers use Bootstrap for the responsive framework. Bootstrap is awesome but it has quirks. First and foremost is the full-height class. It has a hard coded max-width of 1330px; which doesn't make any sense.
I recommend removing the full-height class since, as an iframe, this will inherit the parent container's width while remaining responsive. Next, I would change the grid layout. Change the pf-nav container to col-lg-2 and pf-playlist-view container to col-lg-10.