How can I properly reflect different levels of headers with position:sticky?

Question

I'd like an elegant way to "collect" multi-level headers at the top of the window as the user scrolls, and position:sticky gets me 90% of the way there. The snippet below works just as I'd like it to with one exception: when Header 2b reaches the top, Header 3b is still visible. Since Header 3b is meant to be a "child" of Header 2a, I'd like it to either scroll away or somehow be hidden once Header 2b reaches the top. (Predictably, Header 1b and Header 2d both have the same issue.)

I know that what I have here is how the CSS is supposed to work, but is there an elegant way to make it work the way I'm asking? I've tried giving p a background-color of white and messing with z-index but I haven't had any luck.

h1, h2, h3 {
  position: -webkit-sticky;
  position: sticky;
  top: 0px;
}

h1 {
  background-color: red;
  height: 35px;
}
h2 {
  background-color: blue;
  height: 25px;
  top: 35px;
}
h3 {
  background-color: green;
  height: 20px;
  top: 60px;
}

<h1>Header 1a</h1>
<p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
<h2>Header 2a</h2>
<p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
<h3>Header 3a</h3>
<p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
<h3>Header 3b</h3>
<p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
<h2>Header 2b</h2>
<p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
<h3>Header 3c</h3>
<p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
<h3>Header 3d</h3>
<p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
<h1>Header 1b</h1>
<p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
<h2>Header 2c</h2>
<p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
<h3>Header 3e</h3>
<p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
<h3>Header 3f</h3>
<p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
<h2>Header 2d</h2>
<p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
<h3>Header 3g</h3>
<p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
<h3>Header 3h</h3>
<p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>

Answer 1

I think the logical way to do this is to consider nested divs like below:

h1,
h2,
h3 {
  position: -webkit-sticky;
  position: sticky;
  top: 0px;
  margin:0;
}

h1 {
  background-color: red;
  height: 35px;
  z-index:3;
}

h2 {
  background-color: blue;
  height: 25px;
  top:35px;
  z-index:2;
}

h3 {
  background-color: green;
  height: 20px;
  top:60px;
  z-index:1;
}

<div>
  <h1>Header 1a</h1>
  <p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
  <div>
    <h2>Header 2a</h2>
    <p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
    <div>
      <h3>Header 3a</h3>
      <p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
      <h3>Header 3b</h3>
      <p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
    </div>
  </div>
  <div>
    <h2>Header 2b</h2>
    <p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
    <div>
      <h3>Header 3c</h3>
      <p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
      <h3>Header 3d</h3>
      <p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
    </div>
  </div>
</div>
<div>
  <h1>Header 1b</h1>
  <p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
  <div>
    <h2>Header 2c</h2>
    <p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
    <div>
      <h3>Header 3e</h3>
      <p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
      <h3>Header 3f</h3>
      <p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
    </div>
  </div>
  <div>
    <h2>Header 2d</h2>
    <p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
    <div>
      <h3>Header 3g</h3>
      <p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
      <h3>Header 3h</h3>
      <p>Lorem ipsum dolor sit amet, no qui quis eloquentiam.</p>
    </div>
  </div>
</div>

Answer 2

You need to use the 'z-index' tag in order to do so. First header should have lower z-index value than any other header. The last header should have the highest z-index value. z-index tag is used to put the elements below or above any other elements.