I have been using this extension since I started having problems with the buil-in "reader view" which is part of the firefox browswer. I like to change things like background colors, et cetera and recent versions of the firefox browswer, e.g. 70 and 71, appear to ignore userContent.css, (even if one sets toolkit.legacyUserProfileCustomizations.stylesheets to the value of "true"). I would like to know whether Alexey Kuznetsov's "reader view" can be customized, (background colors, etc), i.e. if does not ignore userContent.css. and if it can, what are the name of the relevant css variables. Right now I have changed the colors, etc, by modifying the xpi file. That is not so convenient, as I am forced to run Alexey's "reader view" in debug mode.