Technically, the iFrame itself is not responsive but that is what the library does: it wraps it in a container that has more responsive properties than the iFra

Technically, the iFrame itself is not responsive but that is what the library does: it wraps it in a container that has more responsive properties than the iFrame. In addition, I think you may be overloading the word "responsive." This is not a post-message base iFrame resizer, it makes iFrames scale like images. This maintains an aspect ratio which is very desirable in many cases. Think a YouTube embed.