Z-Index of Material Dropdown component not layering underneath a fixed div when opened

The problem is that mat-tab-body has z-index: 1 and this won't allow your fixed view inside to have a higher elevation. You can remove the z-index from mat-tab-body put then your content without a z-index won't be clickable anymore so you have to add a z-index and position to your not fixed content.

The code would have to look something like this:

<mat-tab>
  <mat-tab-body> <!-- <-- added automatically -->
    <div class="tab-header"></div>
    <div class="tab-content"></div>
  </mat-tab-body>
</mat-tab>

::ng-deep mat-tab-body {
  z-index: unset !important;
}

.tab-header {
  position: fixed;
  z-index: 1001;
}

.tab-content {
  position: relative;
  z-index: 1;
}