JSFiddle - React, Tailwind, and code Playground

HTML

<div id="triangulo"></div>
<br/>
<div id="trianguloinvertido"></div>
<br/>
<div id="trianguloizquierda"></div>
<br />
<div id="trianguloderecha"></div>

CSS

#trianguloizquierda{
	  width: 0;
	  height: 0;
	  border-top: 50px solid transparent;
	  border-bottom: 50px solid transparent;
	  border-right:50px solid black;
	}
	 
#trianguloderecha {
	  width: 0;
	  height: 0;
	  border-top: 50px solid transparent;
	  border-bottom: 50px solid transparent;
	  border-left: 50px solid black;
	}

#triangulo {
	  width: 0;
	  height: 0;
	  border-left: 50px solid transparent;
	  border-right: 50px solid transparent;
	  border-bottom: 50px solid black;
	}

#trianguloinvertido {
	  width: 0;
	  height: 0;
	  border-left: 50px solid transparent;
	  border-right: 50px solid transparent;
	  border-top: 50px solid black;
	}