JSFiddle - React, Tailwind, and code Playground

HTML

<div class="modal">
    Aspect is kept.
</div>

CSS

.modal {
    position: absolute;
    height: 0px;
    width: 80%;
    padding-bottom: calc(800% * 9 / 16);
    background-color: #F00;
    margin: auto;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
}