The prefs framework includes preferences for text size, line space, and letter space. Currently the lowest value is the default/unchanged value. However, we should allow the user to decrease the size/spacing. This could be because the default size used on the site is too large, because of the font selected, and etc.
Note for some values, like letter-spacing, decreasing the value can result in overlapping text. Caren mentioned that even if a lower value isn't used, it is still useful to help a user understand what the effects of changing the preference are.