iframe width and alignment

Hello Danny,

meanwhile I use your theme for building a second website, as I like it a lot. It’s not overloaded and helps me to create beautiful websites with Gutenberg blocks. Today I came across an issue which I could not solve entirely.

I want to embedd a Youtube video in the enhanced privacy mode (mandatory in the EU). That means I cannot embedd it as a video block, but need to use the following HTML:

<iframe width="560" height="315" src="https://www.youtube-nocookie.com/embed/WXme-fPJoss" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Initially the video was aligned to the left of the screen, which looks awful. I could solve this by adding the following inline CSS:
style=" display: block;".

However the video thumbnail is still the same width as the text, despite the video size being 516×315. I think this might be due to the following CSS, which I found in the style.css file:

/* Make sure embeds and iframes fit their containers. */
embed,
iframe,
object {
	max-width: 100%;
	width: 100%
}

This means that width and maximum width are the same. Doesn’t make sense to me.
How can I change the width so that it is taken from the iframe settings? I have tried adding custom CSS

iframe, object {
width: auto;
}

but that made it worse as now all iframes had width 300.

The site is not public yet, thus I cannot provide a link.

Thanks for your support!
Wiebke