JSFiddle - React, Tailwind, and code Playground

HTML

<div class="menu" id="menu1">
<a href="/html.html">HTML</a> 
<a href="/css.html">CSS</a> 
<a href="/js.html">JS</a> 
</div>
<div class="menu" id="menu2">
<a href="/css/css3.html">CSS3</a><br/>
<div>
<a href="/css/css3/transform.html">transform</a><br/>
<a href="/css/css3/transform-origin.html">transform-origin</a><br/>
<a href="/css/css3/transform-style.html">transform-style</a><br/>
</div>
</div>

CSS

body { font: 14px normal Times, serif; }
div { border: 1px solid #ccc; padding: 5px; margin: 5px; }
a { text-decoration: none; color: #3c3vff; }
.xyz1 { color: #0F0; }
.xyz2 { color: #FF0; }
.xyz3 { color: #F00; }

JavaScript

(()=>{
	const uriWithoutParams='/css/css3/transform.html'.split(/[#|?]+/i).shift();
	const extension=uriWithoutParams.split('.').pop();
	const uriParts=uriWithoutParams.replace('.'+extension,'').split('/').filter(part=>part.length);
	const getClassName=index=>'xyz'+index;
	
	uriParts.forEach((uri,index)=>{
		uri='/'+uriParts.slice(0,++index).join('/')+'.'+extension;
		const className=getClassName(index);
		
		document.querySelectorAll(`a[href="${uri}"]`).forEach(node=>{
			node.classList.add(className);
		});
	});
})();