Hide scrollable content behind transparent fixed position divs when scrolling the page?

Question

I have a div called header that is set up with a fixed position. The problem is when I scroll the page the content of the page shows up behind the header (the header is tran

Answer 1

Just came up with a new solution to this type of problem that I'm quite happy with.

Use clip-path on the content that needs to hide behind the transparent element. Then update the clip-path dynamically with js on window scroll.

HTML

Sticky content

  

JS

window.addEventListener("scroll",function(){
  const windowScrollTop = window.scrollTop;
  const elementToHide = document.getElementById("content");

  elementToHide.style.clipPath = `inset(${windowScrollTop}px 0 0 0)`;
});

Dynamic sticky content

In my case I had an element that I switched to position: sticky after scrolling past it. The #sticky content needs to be relative to the dom elements that came before it until we have scrolled far enough. Here's how I accounted for that:

HTML

Here's some other stuff
Sticky content

  

JS

window.addEventListener("scroll",function(){
  const windowScrollTop = window.scrollTop;
  const stickyElement = document.getElementById("sticky");
  const elementToHide = document.getElementById("content");
  const stickyElementTop = stickyElement.getBoundingClientRect().top

  if(windowScrollTop >= stickyElementTop){
    stickyElement.style.position = "sticky";
    elementToHide.style.clipPath = `inset(${windowScrollTop - stickyElementTop}px 0 0 0)`;
  }
  else {
    stickyElement.style.position = "relative";
    elementToHide.style.clipPath = "none";
  }
});