JSFiddle - React, Tailwind, and code Playground

HTML

<table bgcolor="006FFF" width=50% height=50%><tr><td align="center" >
<table class="transparent" width=50% height=50% class="semi"><tr><td align="center">

<table bgcolor="green" width=50% height=50% class="semik"><tr><td>
Эта таблица должна быть непрозрачной.
</td></tr></table>

</td></tr></table>
</td></tr></table>

CSS

.transparent {background: transparent;}