Hugo Youtube shortcode broken in Outpost theme

I’m a bit out of my depth here, but I used Hugo shortcode to embed a video and it looks good on a full sized browser screen, but it starts getting cropped as you shrink the browser horizontally. The play controls disappear with half the video, while it’s completely unusable on a smaller device like phone.

Any ideas of how I can fix that? This is the post in question:

I think I fixed it by going straight to HTML, seems to work ok. For future reference, something like this:

<iframe src="" frameborder="0" allowfullscreen></iframe>