Are you talking about the Secure Socket Layer (SSL)?
Make sure all your links are https://directory/folder/file.ext and not http://directory/folder/file.ext
If you want the links to work with both a secure and non-secure web site, you can start your links with just the slashes and no protocol name and colon. //directory/folder/file.ext
Edit: OPs problem had to do with The Protocol-relative URL
Are protocol-relative URLs relative URLs?
More information: https://www.paulirish.com/2010/the-protocol-relative-url/
2
solved PHP web app is unsecure while I already used pashword hash for password protection [closed]