Elgg don't have css , the css is handled dynamically by elgg.
the css folder is at:
/views/default/css/
unless you are using a non-default theme, in which case the css folder will be the same type of path as i wrote here - contained within the theme folder.
I'd recommend to use a theme or write a new one to make css changes. Don't write over core files.
Rodolfo Hernandez
Arvixe/Elgg Community Liaison
info@elgg.org
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