Custom modal z-index problem

by hartmaj2

HTML

<div class="overlay"> </div>
    
<div class="custom-modal-background">
    <div class="custom-modal" >
        <div class="modal-div">
          <div class="highlighted">
            I want to be in front of everything
          </div>
        </div>
    </div>
</div>

<div class="highlighted">
  I am in front of everything
</div>

<div>
  I am not in front of everything
</div>

CSS

.custom-modal-background {
    position: fixed;
    display: flex;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    align-items: center;
    justify-content: center;
    z-index: 1500; 
}
.custom-modal {
    position: relative;
    display: flex;
    background-color: white;
}

.overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.5);
    z-index: 2000;
}

.highlighted {
    position: relative;
    background-color: yellow;
    z-index: 2100;
}