cannot highlight current page

Hello ppl,

I’m creating a child theme based on theme “Fotogram” and i cannot find the correct way to highlight current page.
what I have in php is like this:

<div class="sidebar" id="leftcol">

<?php wp_nav_menu( array( 'theme_location' => 'side-menu', 'depth' => '1' ) ); ?>

<?php if ( ! dynamic_sidebar( 'sidebar-area' ) ) : ?>

<div class="widgetcontainer">
<h2><?php _e('Pages','fotogram');?></h2>
<ul>
<?php wp_list_pages('sort_column=menu_order&title_li='); ?>
</ul>
</div>

then I don’t know how to define a current page to style it…

sorry for the dumb question ?? Thanks in advance!