When iOS is in dark mode and you enable reader mode on a website the reader background is dark. However the top and bottom borders remain white. When you scroll up the bottom border turns dark until you scroll down, where it turns white again. 
If iOS is in dark mode when enabling reader mode everything should be white text on a dark background. There should not be wide white borders near the top and bottom of the screen.
1.3.18 (6) (WebKit 8620.2.4.10.8)
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