phpBB: how to add banner to the header

Fast tutorial for clickable adaptive (for mobiles) banner to phpBB forum header without plugins (past phpBB extension which I used for banner was vulnerable and spoiled security at my forum):

1. Go to /styles/prosilver/template/overall_header.html
2. Right after
   <!-- EVENT overall_header_headerbar_before -->
   add:
   <center><a href="LINK_WHERE_BANNER_MUST_LEAD" target="_blank"><img width="100%" src="LINK_TO_THE_PICTURE"></a></center>
   for example:
   <center><a href="https://www.labirint.ru/books/822167/?p=33449" target="_blank"><img width="100%" src="https://vidforum.ru/images/icons/book.jpg"></a></center>
3. Now clean cache – delete folder: cache/production/twig
4. Enjoy your banner! It will be adaptive, which means that it will be shown on mobile devices in proper proportions.

Hope to see your comments! 🙂