271themesdonotbehavelike243
The difference shown by the inspector is more a difference in how the inspector reports the information rather than a difference in the CSS itself. As the screenshot shows, _reboot.scss is indicated in the newer case, but this is a SCSS file whose content, after the compiling process that is done to produce the theme stylesheets, becomes part of feb12.css. The inspector is just giving more specific information about the initial source of those CSS rules.
I'm not sure if the difference is due to a change in how the browser inspector works, or in how the Tiki SCSS compiling process works but, in any case, _reboot.scss establishes some basic defaults and then the theme styles are added below in the stylesheet and will override the reboot properties where desired.
-- Gary