JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div class="hidmeinfirefox">I should be hidden in firefox</div>
</div>

CSS

.container {
}
@-moz-document url-prefix() {
    .container .hidmeinfirefox {
        height: 1px;
        width: 1px;
        overflow: hidden;
    }
}