Apologies, kraxen72’s snippet doesn’t appear to take care of the headings. I thought it did. 
It’s still nice though. I used it for a long time.
To remove all headings in embeds universally without adding any alt/attribute text ( ![[File Name#Heading Name|no-h1]], etc.) like in SlRvb’s snippet, you could try this:
.internal-embed :is(h1,h2,h3,h4,h5,h6) {
display: none;
}