When you will open your IDE site, you will see that all the theming is missing from the site.
This issue happens because the IDE uses
https and the resources(CSS & JS) are called using
http. To resolve this issue, you need to remove the
https from the IDE URL and load it with
http. Changing the Web IDE address to
http://... (removing the
s) will solve this.
Cause (this is optional)
This issue is occurring with Drupal 7 sites only because of mixed content issue, detailed information regarding this is available here https://www.drupal.org/https-information