Embed Iframe

Hi Tom,

I want to embed a website with sportresults in to my webpage. I found this, https://benmarshall.me/responsive-iframes/.

In the code there is no width and height, when I use it in my post there is an WxH created. (it's automatically hardcoded into the post itself after saving overwriting the css) Can you tell my if this is an Wordpress or an GeneratePress issue - then I know in what corner I should look for an answer -

Thanks in advance,

Maarten