No, this is not a real Sinatra error :).
This is the personal homepage of Elad Meidar, a web developer and an entrepreneur specializing in Ruby on Rails. I hang around in Israel, and i am currently having the best time of my life over at Fiverr.com
I am a proud member of RailsBridge, Helping new Rails developers get into our world and also contributed a few Patches to the Ruby on Rails core.
What? you don’t keep your CSS arranged and clean? you deserve a place in hell.
Now seriously, in CSS files as we all know, there is not importance to inner attribute order but only to the order of the selectors you specify, the latest selector that matches, will run down previous attributes if the same attributes were specified in several selectors.
Styleneat let’s you organize your CSS files in an alphabetical attributes order (and selectors too, but just don’t, please).
You're seeing this error because I think it is funny.