PHP equivalent of "modern" sass/less

sass-less.php

<?php 
// index.php
/* We assume that a designer will ask us one day to increase/decrease all body texts
    this website was made in 2010 and we're changing platform now but "sure" this is
    going to happen soon :D "In the next project" :-d
   Also Search & replace '1em' is very trixy, cannot be done reaaallly! IMPOSSIBLE!
*/
$GLOBALS['fontSizeDefault'] = '1em';
class MixinC { // ... }
class MixinB extends MixinC { // ... }
class MixinA extends MixinB { // ... }

// controller/routeX.php
$GLOBALS['fontSizeDefaultCurrent'] = $GLOBALS['fontSizeDefault'];

// Component.php
$GLOBALS['fontSizeDefaultCurrentPage'] = $GLOBALS['fontSizeDefaultCurrent'];

class Component extends MixinA
{
    public $fontSize = $GLOBALS['fontSizeDefaultCurrentPage'];
    
    public __construct() {
        // damn... designer wanted different for this component
        // lets undo all these cool useful mixins and variables
        $this->fontSize = '1.2em'; 
    }
}

Yes, one should never do that. But you can produce bad code with any language. I think both Sass and Less warn in documentation to be careful with deep nesting (or they should).