After figuring out how to customise embedded posts a bit I was still annoyed by the fact that they were all bright white on my dark-themed website.
Thus i spent some more time fiddling with embedded post customisation until I figured out this:
/**
* Customises the style/colours of embedded posts.
*/
add_action( 'embed_head', 'embed_styles' );
/**
* Embed the plugin's custom styles.
*/
function embed_styles() {
echo <<<CSS
<style>
.wp-embed {
background-color:#ccc;
color:#444;
}
</style>
CSS;
}Apparently you can apply “custom styles” to embedded posts.
