The only http asset I can see on that page is '<img alt="Creative Commons License" style="border-width:0;vertical-align:middle;" src="http://i.creativecommons.org/l/by/2.0/uk/80x15.png" />' That server appears to do https so perhaps this can be easily fixed by changing to https for that png; unless of course it will result in http renders issuing warnings ;).
The only http asset I can see on that page is '<img alt="Creative Commons License" style=" border- width:0; vertical- align:middle; " src="http:// i.creativecommo ns.org/ l/by/2. 0/uk/80x15. png" />' That server appears to do https so perhaps this can be easily fixed by changing to https for that png; unless of course it will result in http renders issuing warnings ;).