Embedded iFrame-Player does not look the same as the player from source

[THRY]

I want to embed the podlove web player as iframe into another website. Problem is that the embedded player looks completely different from the source player, where i did copy the iframe-code. All buttons (i.e. for chapters and downloads) are missing and the player is very small (only 300px wide).

Player should look like this: https://podcast.metron.ch/episode/das-ist-eine-test-episodesdfsfd/

And this is how the embedded player looks like, when pasting the iframe code into another website:

Is this a known issue? Did anyone experience the same problem? Any solution to that?