The problem: you click a jump link like
<a href="#header-3">Jump</a> which links to something like
<h3 id="header-3">Header</h3>. That’s totally fine, until you have a
position: fixed; header at the top of the page obscuring the header you’re trying to …
Over at Medium, Jon Moore recently identified "non-rectangular headers" as a tiny trend. A la: it's not crazy popular yet, but just you wait, kiddo.
We're talking about headers (or, more generally, any container element) that have a non-rectangular shape. Such as trapezoids, complex geometric shapes, rounded/elliptical, or even butt-cheek shaped.