JSFiddle - React, Tailwind, and code Playground

HTML

<div>
		<span>15</span>
		<span>Septembre</span>
	</div><!--
 --><div></div>

CSS

html, body {margin:0;}
div:first-child {position:absolute;height:69px;padding:0 10px;transform-origin:100% 0;transform:translateX(-100%) rotate(-90deg);background:yellow;}
div+div {width:100px;height:100px;margin-left:70px;background:red;}
span {display:block;font:120% sans-serif;}
span:first-child {float:right;margin-top:6px;transform:rotate(90deg);}
span+span {font:700 150% sans-serif;}