YUI Dependency Configurator is a great tool for getting a single unified JS or CSS instead of several css/js files. Only problem with that is it doesn't works over "HTTPS". Browser's like Internet Explorer fail to load a web page delivered over HTTPS containing JS/CSS delivered over un-secure(HTTP) URLs.

The good news is that YUI team left a great possibility to change the combo base for service. “Combo base”  is basically YUI combo service base dir. Ex: “http://yui.yahooapis.com/combo?”.

Read More: https://abhinav.fyi/secure-yui-combo-service-over-https/