https - ssl - relative path approach not working?

[snonceino]

I am using a master page layout etc, so all the pages have some parts of it coming from one master page or another. Now, checkout is one of these pages, and it needs to be secure. In my master page, I am using relative path to images and Url's, and these images end up with "http". I thought that if I am using relative path, my master page AND css file automatically use https instead of http if the page is secure? Apparently it does not, when I right click on an image, it still has "http" instead of "https" ans same goes for URL path.