title: Getting mixed content warning - WordPress behind nginx-proxy with letsencrypt ssl
body: <p>I have a WordPress site running in Docker behind nginx with HTTPS (Letsencrypt), but I am having trouble with some essential scripts that won't load because the browser claims they are unauthenticated. I also see the dreaded 'Skip to content' link on the homepage. I set things up with jwilder/nginx-proxy and the letsencrypt companion. All my site data is loaded from a MySQL dump, and my initial assumption was that I had to change all the <code>http://example.org</code> entries in the dump file to <code>https://example.org</code>. However I was getting a 301 redirect with that ('too many redirects' error in the browser), so I changed all the links back to http. Now the site loads, but with the unathenticated error (if I accept the unauthenticated links the site loads, of course).</p>
  
  <p>I have seen <a href="https://stackoverflow.com/a/49096266/795131">several</a> <a href="https://wordpress.stackexchange.com/a/279984">solutions</a> to this, or what I think might be solutions, which all seem to involve adding entries to .htaccess and/or wp-config.php. Indeed adding the following to my wp-config.php seems to solve the 'Skip to content' issue:</p>
  
  <pre><code>/** SSL */  
  define('FORCE_SSL_ADMIN', true);  
  // in some setups HTTP_X_FORWARDED_PROTO might contain  
  // a comma-separated list e.g. http,https  
  // so check for https existence  
  if (strpos($_SERVER['HTTP_X_FORWARDED_PROTO'], 'https') !== false)  
      $_SERVER['HTTPS']='on';
  </code></pre>
  
  <p>However some pages are still complaining about unauthenticated content, and that the site is not fully secure... Not sure what else to do. Do I need to modify .htaccess too?</p>