There are some images, which aren't loaded over https:
(why this is potentially a problem, see: https://developer.mozilla.org/en-US/docs/Security/MixedContent#Mixed_passivedisplay_content)
- /features (lots of image here)
You can confirm this by opening your console (Ctrl-Shift-K on Firefox and Ctrl-Shift-C on Chrome).
As far as I have tested that, it is no problem to load them over https.