If you just upgraded to Link Library 4.1.x, then you might be a bit puzzled with the plugin no longer reading your custom stylesheet.
This is because I created a new stylesheet editor right in the Link Library configuration page. This will avoid problems with future upgrades.
Now, in some case, the upgrade process does not seem to always import the old stylesheet into the Link Library settings. If that is the case, please just copy/paste the contents of your stylesheet into the editor. Or, if you had never made changes to the default stylesheet but still lost your styles, go to the stylesheet editor and press Reset to default.
I hope you are enjoying the new updates.