Htmlviewer

I have a constant kVimeoEmbedGetUp with the following code (Video on Vimeo)

<iframe {position:absolute;top:0;left:0;width:100%;height:100%;} src="https://player.vimeo.com/video/437024146" width="640" height="1138" frameborder="0" allow="autoplay; fullscreen" allowfullscreen></iframe>

I then use HTMLViewer1.loadPageXC(kVimeoEmbedGetUp) to display the page. When I play the video it fills the screen, but the initial image of the video with the play button on it only fills 2/3rd of the screen and isn’t centred. Is there a way to fix this?

If I load the same video with
HTMLViewer1.LoadURL(“https://appdata.sf.com/AppData/Practice_on_Land_V2.mp4”)
It loads and is centred on the screen and then plays full screen