Rated 5 out of 5 stars
A recent (July 14, 2015) reviewer at the Mozilla download webpage for the Stylish add-on criticizes the Firefox version of Stylish saying that, "Shockingly, this extension [Stylish] does not support per-url filtering. The [Google browser] Chrome version of Stylish includes in the editor a URL filter including regexp that allows each style to be applied to only specific sites."
Yet, as indicated in the Stylish Tools add-on description, specifically under "#3 - Write Style for (this URL, etc.)", this criticism is corrected by Stylish Tools, when used together with the Stylish add-on version for Firefox.
I have not yet confirmed this by using Stylish Tools myself (and won't be able to for at least another month or so). Still it is worth pointing out this indicated improvement immediately because it is NOT emphasized in the author's description strongly enough and it really should be.