H5P

The content is adjusted to fit your screen/window size. The user on a desktop can change size of the content by reducing the width of the window. Content should be designed to display on a device with a reason aspect ratio. In your example the image is 500 by 229 which is unusually wide.

The aspect ratio of the Dialog card also depends on the content. Placing a tall picture a card or long text is going to make it so users have to scroll.