JSFiddle - React, Tailwind, and code Playground

HTML

<div id="rd-u">
		<div class=holder-b>
		  <div class="block-b"></div>
		</div>
	</div>

CSS

#rd-u {
	 position: absolute;
	 margin-top: 100px;
	 margin-left: 350px;
	 width: 70px;
	 background-color: #daf;
	 display: block-inline;
	}

	.holder-b {
	  margin-top: 3px;
	  margin-left: 3px;
	  float: left;
	  min-height: 200px;
}

	.block-b {
	  margin-top: 31px;
	  margin-left: 2px;
	  height: 35px;
	  width: 60px;
	  background-color: #d80;
	  display: block;
	}

JavaScript

$(document).ready(function(){

	block_down();	

	function block_down(){
		oval = $(".block-b");
		oval.css('margin-top', '161');
		setTimeout(block_up, 2000);	
	}
	
	function block_up(){
		oval = $(".block-b");
		oval.css('margin-top', '1');
		setTimeout(block_down, 2000);
	}
});