title: Drupal - Mixed content error when using ssl certificate
body: <p>I had a drupal installation working fine. I tried to migrate that one on a Docker Container runing behind a nginx reverse proxy. Everything seems fine but i have some .js and .css files that can't load because in drupal they are linked with http. The error is:</p>
  
  <pre><code>Mixed Content: The page at https://proxy.xx.xx/ was loaded
  over HTTPS, but requested an insecure stylesheet
  http://proxy.xx.xx/sites/default/files/css/css_xE-rWrJf-
  fncB6ztZfd2huxqgxu4WO-qwma6Xer30m4.css'. This request has been
  blocked; the content must be served over HTTPS.
  </code></pre>
  
  <p>I have something like 7 of them and i can't find where those files are called in drupal or how to change the http to https.</p>
  
  <p>Best regards.</p>