Understanding mix-blend-mode

hi! mdn says:

The mix-blend-mode property sets how an element’s content should blend with the content of the element’s parent and the element’s background.

what is unclear to me is what exactly “an element’s content” and “the element’s background” really means. for example, im thinking that “element’s content” should refer to the text content of a div (like the plain text between the

tags) and any children of that div. also, im thinking that the “element’s background” should be the background set by the background property on the element (like background-color).

however, i tested it and it seems i got it wrong. an element with mix-blend-mode on it will blend with everything under it, not just the parent elements content or the background of the element itself.

please, help me make sense of this. any help much appreciated! thanks!