Open Sans google font requested over HTTP instead of HTTPS

Open Sans is blocked because it is requested over HTTP from a page served over HTTPS.

```
Mixed Content: The page at 'https://thinkinglabs.io/' was loaded over HTTPS, but requested an insecure stylesheet 'http://fonts.googleapis.com/css?family=Open+Sans:400,300,600,700,800'. This request has been blocked; the content must be served over HTTPS.
```
