Having eliminated the styling I retested.
What I now understand you want to do is to remove the 'Navigation' and the 'Summary' from the top so you just see the categories or the downloads themselves. In layouts the Navigation is controlled by the Header Section of the currently activated Layout and the Summary is controlled by the Sub-Heading of the currently activated layout. There appears to be a bug with the Category layout.
In List all Categories
the top level categories are shown using the currently activated Categories
In subsequent sub categories and any down loads
the view is controlled by the currently activated Category
Layout. But the sub-header used is the one in the Files Layout which is illogical
- to me this is a bug
as it seems to me that it should be controlled by the sub header in the Category Layout. There may of course be some subtle reason for this as the code goes to some lengths to get both layouts.
If it is to remain this way then it needs a better explanation!
In Single Category it is the currently activated Category
layout, which has the problem as above.
In List All Downloads it is the currently activated Files
In Search it is the currently activated Search
In Single Download it is the currently activated Download Details
You can solve your immediate problem by ensuring the currently activated Files
Layout has the sub-header commented out.