Hi, Magnar,
it's the other way around.
The (e.g.) "flat and modern.css" contains the general bootstrap stuff.
You will see if you compare to bootstrap.css or other themes like cerulean, yeti or so.
This way it is rather easy to change the styling. I used one of the bootstrap themes which you find in "
www.bootswatch.com
" together with the "template.css".
The "template.css" contains the LS specific styles.
And here you are to add your individual stylings.
Best regards
Joffm