Hello Arnel!

Seems you use "Ocean" template. We may advice to switch to another one, or go to the next 2 files from modules/boonex/ocean/data/template/system with names _header.html and __header_js_custom.html, find there line like:href='http://fonts.googleapis.com/css?family=Source+Sans+Pro:200,400,600 and change"http" to "https". Then go to Studio->dasboard->cache and clear all caches.

With the best regards, Leonid