where does Super Cache pull web site style

Hi,

I am new to wordpress and in the process of starting to make some changes to the site. Super Cache is enabled on the site. When I try to make a change to index.html or app.css, the web site does not reflect the change unless I make changes in the super cache directory. But when cache is cleared, those changes are gone. Can you tell me where SP is pulling the root information from? Thanks for being patient with me.

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