Hi Isabella,
For the W3 Total Cache, navigate to Performance > General Settings and do not enable the Page Cache and Minify, make sure you Save Settings & Purge Caches
For the SG Cache, navigate to SG Optimizer > SuperCacher Config turn off the Dynamic Cache and then Purge Cache.
Turn back On your caching when you’re done editing.
Apparently, the W3 Total Cache minifier is very persistent, I excluded the child theme’s style.css file from being minified, please clear your browser’s on your end and your friend’s computer.
Hope it helps,
Cheers!