How to raise bootstrap button "over" a stretched link?

I'd like to put some content in a Bootstrap 4 card with a stretched link over it. I'd also like to include a button in this card which has a URL different to the stretched link.

Bootstrap's documentation says:

Multiple links and tap targets are not recommended with stretched links. However, some position and z-index styles can help should this be required.

But I can't get it to work.

I've tried things like setting the z-index of the button to 5000, but it's still not clickable.

    <div class="card">
        <div class="card-body">
            <div class="row">
                <div class="col align-self-center">
                    <h5 class="card-title">This is a card</h5>
                    <h6 class="card-subtitle mb-2 text-muted">It has a button in it</h6>
                    <p class="card-text">How do I make the button rise up above the stretched link?</p>
                </div>
                <div class="col-auto align-self-center">
                    <a class="btn btn-primary" href="https://www.stackoverflow.com" role="button">Button Link</a>
                </div>
                <a href="https://www.duckduckgo.com" class="stretched-link"></a>
            </div>
        </div>
    </div>

card example

I'd like to make it so the button is clickable without the stretched link covering it.

Any tips?

Setting the button to have the same z-index as the stretched-link will make the button clickable:

.card .btn {
    z-index: 1;
}