How can I overflow item from a grid to another grid in the same hierachy?

I have a container div, inside with a header and body div (both are grid display) to recreate a table with scrollable and sticky header, following this guide. But I have an additional requirement which is to collapse the header and span it across the body to be something like this.
.
So my plan is to have a positioned absolute item inside the grid and set the width to span across the body also.

Here is my code HTML

<div class="wrap">
  <div class="headers">
    <div class="scroller syncscroll" name="myElements">
      <div class="track">
        <div class="heading">Heading 1</div>
      </div>
      <div class="track">
        <div class="heading">Heading 2</div>
      </div>
      <div class="track relative">

        <div class="collapsible">Heading 7</div>
      </div>

    </div>
  </div>
  <div class="tracks syncscroll" name="myElements">
    <div class="track">
      <div class="entry">
        <h3>Lorem, ipsum dolor.</h3>
      </div>
      <div class="entry">
        <h3>Lorem, ipsum.</h3>
      </div>
      <div class="entry">
        <h3>Lorem, ipsum.</h3>
      </div>
    </div>
    <div class="track">
      <div class="entry">
        <h3>Lorem, ipsum dolor.</h3>
      </div>
      <div class="entry">
        <h3>Lorem, ipsum.</h3>
      </div>
      <div class="entry">
        <h3>Lorem, ipsum.</h3>
      </div>
    </div>
    <div class="track">
      <div class="entry">
        <h3>Lorem, ipsum dolor.</h3>
      </div>
      <div class="entry">
        <h3>Lorem, ipsum.</h3>
      </div>
      <div class="entry">
        <h3>Lorem, ipsum.</h3>
      </div>
    </div>
  </div>
</div>

CSS

body {
  background: #f5f7fa;
  overflow-x: hidden;
}

.wrap {
  position: relative;
  margin: 10em auto 30em;
  max-width: 500px;
  overscroll-behavior: contain;
}

.headers {
  top: 0;
  position: -webkit-sticky;
  position: sticky;
  z-index: 1;
}

.tracks,
.scroller {
  display: grid;
  grid-template-columns: repeat(7, 200px);
  
  overflow-y: hidden;
  -webkit-overflow-scrolling: touch;
}

.scroller {
  overflow-x: hidden;
}

.tracks {
  overflow: auto;
  scroll-snap-type: x mandatory;
}

.scenes::-webkit-scrollbar,
.scroller::-webkit-scrollbar {
  display: none;
}

.track + .track {
  margin-left: -1px;
}

.relative {
  position: relative;
}

.collapsible {
  top: 0px;
  position: absolute;
  left: 0px;
  width: 100%;
  height: 200px !important;

  background-color: aqua;
  line-height: 30px;
  // max-width: 30px;
  color: white;
  z-index: 9;
  cursor: pointer;
  writing-mode: vertical-lr;
  text-align: center;
}

.heading {
  height: 50px;
  display: flex;
  justify-content: center;
  align-items: center;
  position: -webkit-sticky;
  position: sticky;
  top: 0;
  border: solid #fff;
  border-width: 0 1px;
  z-index: 1;
  background: #efefef;
  font-weight: 700;
}

.entry {
  border: 1px solid #ebebeb;
  border-top: 0;
  background: #fff;
  height: 8em;
  padding: 1em;
}
}

This code pen shows my problem. For some reason, it seems like the collapsible bar (in blue) cannot span outside of the header grid component. Is this a limitation of grid layout or am I missing something? so far, I only find questions to avoid overflowing the grid only

If it is a limitation, is there any other way to achieve something similar.