Problem with template override

I think I must be missing something because it seems so easy. I wanted to override this file:

wireframe\styles\stream.css

So I modified that file and put the new file into:

templates\MYSITETEMPLATE\html\com_easysocial\styles

However, nothing changes. I tried clearing the website cache. I looked at the site in a completely new browser, which wouldn't have a cached version. But nothing changes...

I know I must be missing something small. Any ideas?