JSFiddle - React, Tailwind, and code Playground

HTML

<div>
Einfacher div
</div>

<div class="divMitClass">
div mit Klasse
</div>

<div id="divMitID">
div mit ID
</div>

<div class="divMitClass" id="divMitID">
div mit allem
</div>

CSS

div{
  background-color: green;
}

.divMitClass{
  background-color: blue;
}

#divMitID{
  background-color: red;
}

div.divMitClass#divMitID{
  background-color: yellow;
}