Here's what I get when looking at it no green padlock first off.
From looking at other things on the page with my very limited knowledge it appears to be images requested from an insure source that seems to be causing it example from the page below
(index):1 Mixed Content: The page at 'hxxps://steamcommunity.com/' was loaded over HTTPS, but requested an insecure image 'hxxp://images.akamai.steamusercontent.com/ugc/101725789673581129/E04F46E65B…olation=lanczos-none&output-format=jpeg&output-quality=95&fit=inside|640:*'. This request has been blocked; the content must be served over HTTPS.
When warning sign clicked:
Attackers might be able to see the images you look at on this site and trick you by modifying them.
And top right of my browser is says
Page is trying to load a script from unauthenticated source.
I also scanned the link with virus total
The scanned with grc's https fingerprinting tool.
Domain Name: steamcommunity.com
Certificate Name: store.steampowered.com
Security Certificate's Authentic Fingerprint: EF:A9:87:C6:4D:6B:7B:60:F6:62:4A:37:D1:97:C3:F3:0C:4D:81:8D
when I had a look manually at the finger print it did match.
ef a9 87 c6 4d 6b 7b 60 f6 62 4a 37 d1 97 c3 f3 0c 4d 81 8d
Hope that's a little help probably nothing bad, but maybe someone with much better knowledge would be able to tell more clearly.
The login page seems to be ok green padlock appears and certificate is ok
I'd check your DNS like shadow advised and run a scan for malware using malware bytes and your own antivirus.
To check your dns open command prompt and type ipconfig/all scroll down and you should see 2 entries under the title DNS servers you can then google them if you don't know if they are correct or not.
Edited by HolyCowz, 13 December 2016 - 04:55 PM.