[SarahC_]

That doesn't work on Codepen.io, in the latest Chrome.

Back to the drawing board.

[ramoz]

<div style="display:flex;justify-content:center;align-items:center;">

    <div>I'm centered</div>

</div>

* I wrote the original without testing but it is justify-content, not justify-items... oops

[ramoz]

https://codepen.io/backnotprop/pen/qBvzpvr