Highlight current page with ONE sitemap [Solved]

I hope there is not such a topic, it is kinda hard to search for it. So my problem:

I have a sitemap.php which is "<?php include 'sitemap.php'; ?>" included on every page. Before i made this, i had this sitemap on every single html or php site.

So now: I want to keep this single php file but: If the user clicks on a link, this site he'll be redirected to should be highlighted now. Short: Highlight the current page but with one sitemap-file.

my css for highlighting:

li.active {
  color: #fff;
}

and i guess you all know how a sitemap looks :D

               <ul class="nav nav-menu">
                  <li><a href="channel.php">
                      <div class="nav-menu__ico"><i class="fa fa-fw fa-comment"></i></div>
                      <div class="nav-menu__text"><span>Channel</span></div></a></li>
                  <li><a href="products.html">
                      <div class="nav-menu__ico"><i class="fa fa-fw fa-users"></i></div>
                      <div class="nav-menu__text"><span>Groups</span></div></a></li>
                  <li><a href="groups.php">
                      <div class="nav-menu__ico"><i class="fa fa-fw fa-bars"></i></div>
                      <div class="nav-menu__text"><span>Ranking</span></div></a></li>
                  <li><a href="users.html">
                      <div class="nav-menu__ico"><i class="fa fa-fw fa-user"></i></div>
                      <div class="nav-menu__text"><span>Users</span></div></a></li>
                </ul>

I guess it have to be done with JS / jQuery / PHP... But i really dont know how.

Hope someone out there can help me :)!

Sincerely, Timo