Add "active" class to current link

It doesn’t work in his case because he doesn’t use a loop to construct the menu, so that $page is the same for every menu item. In order for the code snippet to work in his case he’d have to adjust it slightly for each menu item, maybe like so:

...
<li <?php e($site->page('about')->isOpen(), ' class="active"') ?>>...</li>
<li <?php e($site->page('process')->isOpen(), ' class="active"') ?>>...</li>
...