Multiple CSS files

[polyfragmented]

But I'm not familiar with this code, can someone please elaborate this?

Code:

#index header .breadcrumbs { display:none; }

The CSS rule lists the "conditions" which must be met in order to not display an element with the class of "breadcrumbs": It must be a child of the header element which in turn must be a child of an element with the id of "index" (the page's body element in this case). Only that element with class "breadcrumb" would be targeted by this rule, no other element with a class of ".breadcrumb" which might additionally exist on the page outside the header element.

For the Innovation theme, try

Code:

#index aside#sidebar {display: none;}

This translates to: don't display the element "aside" with the id of "sidebar" (the sidebar) on the page with an id of "index" (the start page in GS)

Worked here without flaw.

PS: A few resources you might want to check out: IDs and CLASSes, CSS selectors (decendant, child, sibling,...). The knowledge will help you read CSS rules like the one you posted.