I tried to setup PrimeFlex (3.0.1) for PrimeFaces (10.0.0). I used css files as provided in dist folder of PrimeFlex repo. Also I followed the instructions give
windows-identity
forfiles
gganimate
stored-procedures
sgx
sparse-checkout
sitecore8
slack-api
csrf
dynamic-web-twain
uibutton
analysis
stdmutex
graphicscontext
govmomi
easyimage
diagrams.net
rusqlite
asyncssh
word-list
uialertviewdelegate
sailpoint
pix
acts-as-tree
worksheet-function
angular-ui-typeahead
java-record
fflush
avprobe
instaloader